diff --git a/LICENSE.md b/LICENSE.md
index 83528969..962213dc 100644
--- a/LICENSE.md
+++ b/LICENSE.md
@@ -8,7 +8,7 @@ Licenses of **third-party libraries** are listed in [LICENSE-dist.txt](LICENSE-d
 
 The **Component Library graphics** in the `res/ComponentLibrary` directory are copyright © 2018 [Grayscale](http://grayscale.info/) and licensed under [CC BY-NC 4.0](https://creativecommons.org/licenses/by-nc/4.0/). Commercial plugins must request a commercial license to use Component Library graphics by emailing contact@vcvrack.com.
 
-The **Core panel graphics** in the `res/Core` directory are copyright © 2018 [Grayscale](http://grayscale.info/) and licensed under [CC BY-NC-ND 4.0](https://creativecommons.org/licenses/by-nc-nd/4.0/). You may not distribute modified adaptations.
+The **Core panel graphics** in the `res/Core` directory are copyright © 2018 [Grayscale](http://grayscale.info/) and licensed under [CC BY-NC-ND 4.0](https://creativecommons.org/licenses/by-nc-nd/4.0/). You may not create derivative works.
 
 The **VCV logo and icon** are copyright © 2017 Andrew Belt and may not be used in derivative works.
 
diff --git a/include/app.hpp b/include/app.hpp
index 69c4be07..a0fce24b 100644
--- a/include/app.hpp
+++ b/include/app.hpp
@@ -1,8 +1,8 @@
 #pragma once
+#include "ui.hpp"
 #include "app/AudioWidget.hpp"
 #include "app/CircularShadow.hpp"
 #include "app/common.hpp"
-#include "app/Component.hpp"
 #include "app/Knob.hpp"
 #include "app/LedDisplay.hpp"
 #include "app/LightWidget.hpp"
diff --git a/include/app/CircularShadow.hpp b/include/app/CircularShadow.hpp
index c3d189c3..e78b17a1 100644
--- a/include/app/CircularShadow.hpp
+++ b/include/app/CircularShadow.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/TransparentWidget.hpp"
 #include "app/common.hpp"
 
 
diff --git a/include/app/Component.hpp b/include/app/Component.hpp
deleted file mode 100644
index b499dd4e..00000000
--- a/include/app/Component.hpp
+++ /dev/null
@@ -1,17 +0,0 @@
-#pragma once
-#include "app/common.hpp"
-
-
-namespace rack {
-
-
-struct Module;
-
-
-/** A Widget that exists on a Panel and interacts with a Module */
-struct Component : OpaqueWidget {
-	Module *module = NULL;
-};
-
-
-} // namespace rack
diff --git a/include/app/Knob.hpp b/include/app/Knob.hpp
index 8ea9c796..269ca980 100644
--- a/include/app/Knob.hpp
+++ b/include/app/Knob.hpp
@@ -6,17 +6,40 @@
 namespace rack {
 
 
+static const float KNOB_SENSITIVITY = 0.0015f;
+
+
 /** Implements vertical dragging behavior for ParamWidgets */
 struct Knob : ParamWidget {
-	/** Snap to nearest integer while dragging */
-	bool snap = false;
 	/** Multiplier for mouse movement to adjust knob value */
 	float speed = 1.0;
-	float dragValue;
-	Knob();
-	void onDragStart(event::DragStart &e) override;
-	void onDragMove(event::DragMove &e) override;
-	void onDragEnd(event::DragEnd &e) override;
+
+	void onDragStart(event::DragStart &e) override {
+		windowCursorLock();
+	}
+
+	void onDragEnd(event::DragEnd &e) override {
+		windowCursorUnlock();
+	}
+
+	void onDragMove(event::DragMove &e) override {
+		if (quantity) {
+			float range;
+			if (quantity->isBounded()) {
+				range = quantity->getRange();
+			}
+			else {
+				// Continuous encoders scale as if their limits are +/-1
+				range = 2.f;
+			}
+			float delta = KNOB_SENSITIVITY * -e.mouseDelta.y * speed * range;
+
+			// Drag slower if Mod is held
+			if (windowIsModPressed())
+				delta /= 16.f;
+			quantity->moveValue(delta);
+		}
+	}
 };
 
 
diff --git a/include/app/LedDisplay.hpp b/include/app/LedDisplay.hpp
index 30e5ebb0..915b0c1e 100644
--- a/include/app/LedDisplay.hpp
+++ b/include/app/LedDisplay.hpp
@@ -1,11 +1,14 @@
 #pragma once
+#include "widgets/Widget.hpp"
+#include "widgets/TransparentWidget.hpp"
+#include "ui/TextField.hpp"
 #include "app/common.hpp"
 
 
 namespace rack {
 
 
-struct LedDisplay : virtual Widget {
+struct LedDisplay : VirtualWidget {
 	void draw(NVGcontext *vg) override;
 };
 
diff --git a/include/app/LightWidget.hpp b/include/app/LightWidget.hpp
index 536a6439..e48c03bb 100644
--- a/include/app/LightWidget.hpp
+++ b/include/app/LightWidget.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/TransparentWidget.hpp"
 #include "app/common.hpp"
 
 
diff --git a/include/app/ModuleWidget.hpp b/include/app/ModuleWidget.hpp
index de272153..eafb10fb 100644
--- a/include/app/ModuleWidget.hpp
+++ b/include/app/ModuleWidget.hpp
@@ -1,5 +1,10 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
+#include "ui/Menu.hpp"
 #include "app/common.hpp"
+#include "app/SVGPanel.hpp"
+#include "app/Port.hpp"
+#include "app/ParamWidget.hpp"
 #include "plugin.hpp"
 #include "engine.hpp"
 
diff --git a/include/app/ParamQuantity.hpp b/include/app/ParamQuantity.hpp
new file mode 100644
index 00000000..d0fda26d
--- /dev/null
+++ b/include/app/ParamQuantity.hpp
@@ -0,0 +1,57 @@
+#pragma once
+#include "ui/Quantity.hpp"
+#include "engine.hpp"
+
+
+namespace rack {
+
+
+/** A Quantity that wraps an engine Param */
+struct ParamQuantity : Quantity {
+	Module *module = NULL;
+	int paramId = 0;
+	/** Use engine smoothing of Param values */
+	bool smooth = false;
+	/** Snap to the nearest integer */
+	bool snap = false;
+	float snapValue = 0.f;
+
+	Param *getParam() {
+		assert(module);
+		return &module->params[paramId];
+	}
+
+	void commitSnap() {
+		// TODO
+	}
+
+	void setValue(float value) override {
+		// TODO Smooth
+		// TODO Snap
+		getParam()->value = value;
+	}
+	float getValue() override {
+		return getParam()->value;
+	}
+	float getMinValue() override {
+		return getParam()->minValue;
+	}
+	float getMaxValue() override {
+		return getParam()->maxValue;
+	}
+	float getDefaultValue() override {
+		return getParam()->defaultValue;
+	}
+	std::string getLabel() override {
+		return getParam()->label;
+	}
+	std::string getUnit() override {
+		return getParam()->unit;
+	}
+	int getPrecision() override {
+		return getParam()->precision;
+	}
+};
+
+
+} // namespace rack
diff --git a/include/app/ParamWidget.hpp b/include/app/ParamWidget.hpp
index 03ebad64..00546bc2 100644
--- a/include/app/ParamWidget.hpp
+++ b/include/app/ParamWidget.hpp
@@ -1,4 +1,6 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
+#include "app/ParamQuantity.hpp"
 #include "app/common.hpp"
 #include "engine.hpp"
 
@@ -6,22 +8,23 @@
 namespace rack {
 
 
-/** A Component which has control over a Param */
-struct ParamWidget : Component, QuantityWidget {
-	int paramId;
-	/** Used to momentarily disable value randomization
-	To permanently disable or change randomization behavior, override the randomize() method instead of changing this.
-	*/
-	bool randomizable = true;
-	/** Apply per-sample smoothing in the engine */
-	bool smooth = false;
+/** Controls a ParamQuantity */
+struct ParamWidget : OpaqueWidget {
+	ParamQuantity *quantity;
 
-	json_t *toJson();
+	ParamWidget() {
+		quantity = new ParamQuantity;
+	}
+
+	~ParamWidget() {
+		delete quantity;
+	}
+
+	/** For legacy patch loading */
 	void fromJson(json_t *rootJ);
 	virtual void reset();
 	virtual void randomize();
 	void onButton(event::Button &e) override;
-	void onChange(event::Change &e) override;
 };
 
 
diff --git a/include/app/PluginManagerWidget.hpp b/include/app/PluginManagerWidget.hpp
index 72a1d313..95fb5483 100644
--- a/include/app/PluginManagerWidget.hpp
+++ b/include/app/PluginManagerWidget.hpp
@@ -1,11 +1,12 @@
 #pragma once
+#include "widgets/Widget.hpp"
 #include "app/common.hpp"
 
 
 namespace rack {
 
 
-struct PluginManagerWidget : virtual Widget {
+struct PluginManagerWidget : VirtualWidget {
 	Widget *loginWidget;
 	Widget *manageWidget;
 	Widget *downloadWidget;
diff --git a/include/app/Port.hpp b/include/app/Port.hpp
index 4390cdaa..4d4945b3 100644
--- a/include/app/Port.hpp
+++ b/include/app/Port.hpp
@@ -1,17 +1,21 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "app/common.hpp"
+#include "app/MultiLightWidget.hpp"
 
 
 namespace rack {
 
 
-struct Port : Component {
+struct Port : OpaqueWidget {
+	Module *module = NULL;
+	int portId;
+
 	enum PortType {
 		INPUT,
 		OUTPUT
 	};
 	PortType type = INPUT;
-	int portId;
 	MultiLightWidget *plugLight;
 
 	Port();
diff --git a/include/app/RackRail.hpp b/include/app/RackRail.hpp
index eb689c28..d4268062 100644
--- a/include/app/RackRail.hpp
+++ b/include/app/RackRail.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/TransparentWidget.hpp"
 #include "app/common.hpp"
 
 
diff --git a/include/app/RackScene.hpp b/include/app/RackScene.hpp
index b02bb44d..6e83467e 100644
--- a/include/app/RackScene.hpp
+++ b/include/app/RackScene.hpp
@@ -1,10 +1,15 @@
 #pragma once
+#include "ui/Scene.hpp"
 #include "app/common.hpp"
 
 
 namespace rack {
 
 
+struct ScrollWidget;
+struct ZoomWidget;
+
+
 struct RackScene : Scene {
 	ScrollWidget *scrollWidget;
 	ZoomWidget *zoomWidget;
diff --git a/include/app/RackScrollWidget.hpp b/include/app/RackScrollWidget.hpp
index 60aa1876..f695f1d6 100644
--- a/include/app/RackScrollWidget.hpp
+++ b/include/app/RackScrollWidget.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "ui/ScrollWidget.hpp"
 #include "app/common.hpp"
 
 
diff --git a/include/app/SVGButton.hpp b/include/app/SVGButton.hpp
index 267fbd25..28439e61 100644
--- a/include/app/SVGButton.hpp
+++ b/include/app/SVGButton.hpp
@@ -9,7 +9,7 @@ namespace rack {
 /** A Component with a default (up) and active (down) state when clicked.
 Does not modify a Param, simply calls onAction() of a subclass.
 */
-struct SVGButton : Component, FramebufferWidget {
+struct SVGButton : FramebufferWidget {
 	std::shared_ptr<SVG> defaultSVG;
 	std::shared_ptr<SVG> activeSVG;
 	SVGWidget *sw;
diff --git a/include/app/SVGKnob.hpp b/include/app/SVGKnob.hpp
index d73ef852..850b3cc4 100644
--- a/include/app/SVGKnob.hpp
+++ b/include/app/SVGKnob.hpp
@@ -1,6 +1,7 @@
 #pragma once
 #include "app/common.hpp"
 #include "app/CircularShadow.hpp"
+#include "widgets/TransformWidget.hpp"
 
 
 namespace rack {
diff --git a/include/app/SVGPanel.hpp b/include/app/SVGPanel.hpp
index 59bcf260..60e2df79 100644
--- a/include/app/SVGPanel.hpp
+++ b/include/app/SVGPanel.hpp
@@ -1,5 +1,7 @@
 #pragma once
 #include "app/common.hpp"
+#include "widgets/FramebufferWidget.hpp"
+#include "widgets/SVGWidget.hpp"
 
 
 namespace rack {
diff --git a/include/app/Toolbar.hpp b/include/app/Toolbar.hpp
index c1662aca..687fcda1 100644
--- a/include/app/Toolbar.hpp
+++ b/include/app/Toolbar.hpp
@@ -1,4 +1,7 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
+#include "ui/Slider.hpp"
+#include "ui/RadioButton.hpp"
 #include "app/common.hpp"
 
 
@@ -6,10 +9,9 @@ namespace rack {
 
 
 struct Toolbar : OpaqueWidget {
-	Slider *wireOpacitySlider;
-	Slider *wireTensionSlider;
-	Slider *zoomSlider;
-	RadioButton *cpuUsageButton;
+	// TODO Move these to future Rack app state
+	float wireOpacity = 0.5;
+	float wireTension = 0.5;
 
 	Toolbar();
 	void draw(NVGcontext *vg) override;
diff --git a/include/app/common.hpp b/include/app/common.hpp
index 096afd0b..4d91b6b2 100644
--- a/include/app/common.hpp
+++ b/include/app/common.hpp
@@ -1,5 +1,6 @@
 #pragma once
-#include "ui.hpp"
+#include "math.hpp"
+#include <string>
 #include <jansson.h>
 
 
@@ -37,11 +38,4 @@ static const std::string PRESET_FILTERS = "VCV Rack module preset (.vcvm):vcvm";
 static const std::string PATCH_FILTERS = "VCV Rack patch (.vcv):vcv";
 
 
-
-/** Deprecated. Will be removed in v1 */
-json_t *colorToJson(NVGcolor color);
-/** Deprecated. Will be removed in v1 */
-NVGcolor jsonToColor(json_t *colorJ);
-
-
 } // namespace rack
diff --git a/include/componentlibrary.hpp b/include/componentlibrary.hpp
index 8523fdfb..5ce36162 100644
--- a/include/componentlibrary.hpp
+++ b/include/componentlibrary.hpp
@@ -59,8 +59,9 @@ struct RoundHugeBlackKnob : RoundKnob {
 
 struct RoundBlackSnapKnob : RoundBlackKnob {
 	RoundBlackSnapKnob() {
-		snap = true;
-		smooth = false;
+		// TODO
+		// quantity.snap = true;
+		// quantity.smooth = false;
 	}
 };
 
@@ -308,8 +309,9 @@ struct BefacoBigKnob : SVGKnob {
 
 struct BefacoBigSnapKnob : BefacoBigKnob {
 	BefacoBigSnapKnob() {
-		snap = true;
-		smooth = false;
+		// TODO
+		// quantity.snap = true;
+		// quantity.smooth = false;
 	}
 };
 
diff --git a/include/engine.hpp b/include/engine.hpp
index 0b28eba4..30982ce4 100644
--- a/include/engine.hpp
+++ b/include/engine.hpp
@@ -8,7 +8,27 @@ namespace rack {
 
 
 struct Param {
-	float value = 0.0;
+	float value = 0.f;
+	float minValue = 0.f;
+	float maxValue = 1.f;
+	float defaultValue = 0.f;
+	std::string label;
+	std::string unit;
+	int precision = 2;
+
+	// TODO Change this horrible method name
+	void setup(float minValue, float maxValue, float defaultValue, std::string label = "", std::string unit = "", int precision = 2) {
+		this->value = defaultValue;
+		this->minValue = minValue;
+		this->maxValue = maxValue;
+		this->defaultValue = defaultValue;
+		this->label = label;
+		this->unit = unit;
+		this->precision = precision;
+	}
+
+	json_t *toJson();
+	void fromJson(json_t *rootJ);
 };
 
 
diff --git a/include/helpers.hpp b/include/helpers.hpp
index 5132dad4..12a86b42 100644
--- a/include/helpers.hpp
+++ b/include/helpers.hpp
@@ -46,8 +46,8 @@ template <class TParamWidget>
 TParamWidget *createParam(Vec pos, Module *module, int paramId, float minValue, float maxValue, float defaultValue) {
 	TParamWidget *o = new TParamWidget;
 	o->box.pos = pos;
-	o->module = module;
-	o->paramId = paramId;
+	o->quantity->module = module;
+	o->quantity->paramId = paramId;
 	o->setLimits(minValue, maxValue);
 	o->setDefaultValue(defaultValue);
 	return o;
@@ -57,8 +57,8 @@ template <class TParamWidget>
 TParamWidget *createParamCentered(Vec pos, Module *module, int paramId, float minValue, float maxValue, float defaultValue) {
 	TParamWidget *o = new TParamWidget;
 	o->box.pos = pos.minus(o->box.size.div(2));
-	o->module = module;
-	o->paramId = paramId;
+	o->quantity->module = module;
+	o->quantity->paramId = paramId;
 	o->setLimits(minValue, maxValue);
 	o->setDefaultValue(defaultValue);
 	return o;
diff --git a/include/math.hpp b/include/math.hpp
index ac43fe61..2af5190b 100644
--- a/include/math.hpp
+++ b/include/math.hpp
@@ -244,6 +244,12 @@ struct Rect {
 	bool isEqual(Rect r) const {
 		return pos.isEqual(r.pos) && size.isEqual(r.size);
 	}
+	float getLeft() const {
+		return pos.x + size.x;
+	}
+	float getBottom() const {
+		return pos.y + size.y;
+	}
 	Vec getCenter() const {
 		return pos.plus(size.mult(0.5f));
 	}
diff --git a/include/string.hpp b/include/string.hpp
index 4524775c..f52ab531 100644
--- a/include/string.hpp
+++ b/include/string.hpp
@@ -22,6 +22,9 @@ bool endsWith(std::string str, std::string suffix);
 /** Extracts portions of a path */
 std::string directory(std::string path);
 std::string filename(std::string path);
+/** Extracts the portion of a path without the extension */
+std::string basename(std::string path);
+/** Extracts the extension of a path */
 std::string extension(std::string path);
 
 struct CaseInsensitiveCompare {
diff --git a/include/system.hpp b/include/system.hpp
index 6ba1b5ab..3e29c953 100644
--- a/include/system.hpp
+++ b/include/system.hpp
@@ -1,5 +1,5 @@
 #pragma once
-#include <vector>
+#include <list>
 #include "common.hpp"
 
 
@@ -7,7 +7,7 @@ namespace rack {
 namespace system {
 
 
-std::vector<std::string> listEntries(std::string path);
+std::list<std::string> listEntries(std::string path);
 bool isFile(std::string path);
 bool isDirectory(std::string path);
 void copyFile(std::string srcPath, std::string destPath);
diff --git a/include/ui.hpp b/include/ui.hpp
index 00020030..0077a022 100644
--- a/include/ui.hpp
+++ b/include/ui.hpp
@@ -1,6 +1,6 @@
 #pragma once
+#include "widgets.hpp"
 #include "ui/common.hpp"
-#include "ui/QuantityWidget.hpp"
 #include "ui/SequentialLayout.hpp"
 #include "ui/Label.hpp"
 #include "ui/List.hpp"
diff --git a/include/ui/Button.hpp b/include/ui/Button.hpp
index 04d3c007..6829c63a 100644
--- a/include/ui/Button.hpp
+++ b/include/ui/Button.hpp
@@ -1,5 +1,7 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
+#include "ui/Quantity.hpp"
 
 
 namespace rack {
@@ -8,11 +10,18 @@ namespace rack {
 struct Button : OpaqueWidget {
 	std::string text;
 	BNDwidgetState state = BND_DEFAULT;
+	/** Optional, owned. Tracks the pressed state of the button.*/
+	Quantity *quantity = NULL;
 
 	Button() {
 		box.size.y = BND_WIDGET_HEIGHT;
 	}
 
+	~Button() {
+		if (quantity)
+			delete quantity;
+	}
+
 	void draw(NVGcontext *vg) override {
 		bndToolButton(vg, 0.0, 0.0, box.size.x, box.size.y, BND_CORNER_NONE, state, -1, text.c_str());
 		Widget::draw(vg);
@@ -28,10 +37,14 @@ struct Button : OpaqueWidget {
 
 	void onDragStart(event::DragStart &e) override {
 		state = BND_ACTIVE;
+		if (quantity)
+			quantity->setMax();
 	}
 
 	void onDragEnd(event::DragEnd &e) override {
 		state = BND_HOVER;
+		if (quantity)
+			quantity->setMin();
 	}
 
 	void onDragDrop(event::DragDrop &e) override {
diff --git a/include/ui/ChoiceButton.hpp b/include/ui/ChoiceButton.hpp
index 8012c6e2..76d6209a 100644
--- a/include/ui/ChoiceButton.hpp
+++ b/include/ui/ChoiceButton.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "ui/common.hpp"
 #include "ui/Button.hpp"
 
 
diff --git a/include/ui/IconButton.hpp b/include/ui/IconButton.hpp
index f8f42d50..b53d4739 100644
--- a/include/ui/IconButton.hpp
+++ b/include/ui/IconButton.hpp
@@ -1,5 +1,6 @@
 #pragma once
 #include "ui/common.hpp"
+#include "ui/Button.hpp"
 
 
 namespace rack {
diff --git a/include/ui/Label.hpp b/include/ui/Label.hpp
index f427c587..4c23ef6f 100644
--- a/include/ui/Label.hpp
+++ b/include/ui/Label.hpp
@@ -1,11 +1,12 @@
 #pragma once
+#include "widgets/Widget.hpp"
 #include "ui/common.hpp"
 
 
 namespace rack {
 
 
-struct Label : virtual Widget {
+struct Label : VirtualWidget {
 	std::string text;
 	float fontSize;
 	NVGcolor color;
diff --git a/include/ui/List.hpp b/include/ui/List.hpp
index 76ffee03..43bc409b 100644
--- a/include/ui/List.hpp
+++ b/include/ui/List.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 
 
diff --git a/include/ui/Menu.hpp b/include/ui/Menu.hpp
index 581abbf6..fadd852e 100644
--- a/include/ui/Menu.hpp
+++ b/include/ui/Menu.hpp
@@ -1,4 +1,6 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
+#include "ui/common.hpp"
 #include "ui/MenuEntry.hpp"
 
 
diff --git a/include/ui/MenuEntry.hpp b/include/ui/MenuEntry.hpp
index 911da47a..7d38c2ef 100644
--- a/include/ui/MenuEntry.hpp
+++ b/include/ui/MenuEntry.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 
 
diff --git a/include/ui/MenuItem.hpp b/include/ui/MenuItem.hpp
index 75f84c2e..41c2f306 100644
--- a/include/ui/MenuItem.hpp
+++ b/include/ui/MenuItem.hpp
@@ -1,6 +1,6 @@
 #pragma once
 #include "ui/common.hpp"
-#include "ui/MenuOverlay.hpp"
+#include "ui/MenuEntry.hpp"
 
 
 namespace rack {
diff --git a/include/ui/MenuLabel.hpp b/include/ui/MenuLabel.hpp
index f5c0fc58..b63ba2dc 100644
--- a/include/ui/MenuLabel.hpp
+++ b/include/ui/MenuLabel.hpp
@@ -1,5 +1,6 @@
 #pragma once
 #include "ui/common.hpp"
+#include "ui/MenuEntry.hpp"
 
 
 namespace rack {
diff --git a/include/ui/MenuOverlay.hpp b/include/ui/MenuOverlay.hpp
index 295fcca1..dfbd4030 100644
--- a/include/ui/MenuOverlay.hpp
+++ b/include/ui/MenuOverlay.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 
 
diff --git a/include/ui/MenuSeparator.hpp b/include/ui/MenuSeparator.hpp
index 4406ba42..3b471690 100644
--- a/include/ui/MenuSeparator.hpp
+++ b/include/ui/MenuSeparator.hpp
@@ -1,5 +1,6 @@
 #pragma once
 #include "ui/common.hpp"
+#include "ui/MenuEntry.hpp"
 
 
 namespace rack {
diff --git a/include/ui/ProgressBar.hpp b/include/ui/ProgressBar.hpp
index 7e976ea6..bf68a8b4 100644
--- a/include/ui/ProgressBar.hpp
+++ b/include/ui/ProgressBar.hpp
@@ -1,19 +1,26 @@
 #pragma once
 #include "ui/common.hpp"
-#include "ui/QuantityWidget.hpp"
 
 
 namespace rack {
 
 
-struct ProgressBar : QuantityWidget {
+struct ProgressBar : VirtualWidget {
+	Quantity *quantity = NULL;
+
 	ProgressBar() {
 		box.size.y = BND_WIDGET_HEIGHT;
 	}
 
+	~ProgressBar() {
+		if (quantity)
+			delete quantity;
+	}
+
 	void draw(NVGcontext *vg) override {
-		float progress = rescale(value, minValue, maxValue, 0.0, 1.0);
-		bndSlider(vg, 0.0, 0.0, box.size.x, box.size.y, BND_CORNER_ALL, BND_DEFAULT, progress, getText().c_str(), NULL);
+		float progress = quantity ? quantity->getScaledValue() : 0.f;
+		std::string text = quantity ? quantity->getString() : "";
+		bndSlider(vg, 0.0, 0.0, box.size.x, box.size.y, BND_CORNER_ALL, BND_DEFAULT, progress, text.c_str(), NULL);
 	}
 };
 
diff --git a/include/ui/Quantity.hpp b/include/ui/Quantity.hpp
new file mode 100644
index 00000000..ec3dcd0b
--- /dev/null
+++ b/include/ui/Quantity.hpp
@@ -0,0 +1,128 @@
+#pragma once
+#include "string.hpp"
+
+
+namespace rack {
+
+
+/** A controller for manipulating a float value (which subclasses must store somehow) with limits and labels
+Often used as a decorator component for Widgets that read or write a quantity.
+*/
+struct Quantity {
+	virtual ~Quantity() {}
+
+	/** Sets the value directly
+	Override this to change the state of your subclass to represent the new value.
+	*/
+	virtual void setValue(float value) {}
+
+	/** Returns the value
+	Override this to return the state of your subclass.
+	*/
+	virtual float getValue() {return 0.f;}
+
+	/** Returns the minimum allowed value */
+	virtual float getMinValue() {return 0.f;}
+
+	/** Returns the maximum allowed value */
+	virtual float getMaxValue() {return 1.f;}
+
+	/** Returns the default value, for resetting */
+	virtual float getDefaultValue() {return 0.f;}
+
+	/** Returns the value, possibly transformed
+	Useful for logarithmic scaling, multiplying by 100 for percentages, etc.
+	*/
+	virtual float getDisplayValue() {return getValue();}
+
+	/** Sets the value by the transformed display value */
+	virtual void setDisplayValue(float displayValue) {setValue(displayValue);}
+
+	/** The number of decimal places for display
+	A precision of 2 will display as "1.00" for example.
+	*/
+	virtual int getPrecision() {return 2;}
+
+	/** Returns a string representation of the display value */
+	virtual std::string getDisplayValueString() {
+		return string::f("%.*f", getPrecision(), getDisplayValue());
+	}
+
+	/** The name of the quantity */
+	virtual std::string getLabel() {return "";}
+
+	/** The unit abbreviation of the quantity
+	Include an initial space character if you want a space after the number, e.g. "440 Hz". This allows space-less units, like "100%".
+	*/
+	virtual std::string getUnit() {return "";}
+
+	/** Returns a string representation of the quantity */
+	virtual std::string getString() {
+		std::string s;
+		std::string label = getLabel();
+		if (!label.empty())
+			s += label + ": ";
+		s += getDisplayValueString() + getUnit();
+		return s;
+	}
+
+	// Helper methods
+
+	/** Resets the value to the default value */
+	void reset() {
+		setValue(getDefaultValue());
+	}
+
+	/** Checks whether the value is at the min value */
+	bool isMin() {
+		return getValue() <= getMinValue();
+	}
+
+	/** Checks whether the value is at the max value */
+	bool isMax() {
+		return getValue() >= getMaxValue();
+	}
+
+	/** Sets the value to the min value */
+	void setMin() {
+		setValue(getMinValue());
+	}
+
+	/** Sets the value to the max value */
+	void setMax() {
+		setValue(getMaxValue());
+	}
+
+	/** Sets value from the range 0 to 1 */
+	void setScaledValue(float scaledValue) {
+		setValue(rescale(scaledValue, 0.f, 1.f, getMinValue(), getMaxValue()));
+	}
+
+	/** Returns the value rescaled to the range 0 to 1 */
+	float getScaledValue() {
+		return rescale(getValue(), getMinValue(), getMaxValue(), 0.f, 1.f);
+	}
+
+	/** The difference between the max and min values */
+	float getRange() {
+		return getMaxValue() - getMinValue();
+	}
+
+	/** Checks whether the bounds are finite */
+	bool isBounded() {
+		return std::isfinite(getMinValue()) && std::isfinite(getMaxValue());
+	}
+
+	/** Adds an amount to the value */
+	void moveValue(float deltaValue) {
+		setValue(getValue() + deltaValue);
+	}
+
+	/** Adds an amount to the value scaled to the range 0 to 1 */
+	void moveScaledValue(float deltaScaledValue) {
+		moveValue(deltaScaledValue * getRange());
+	}
+};
+
+
+} // namespace rack
diff --git a/include/ui/QuantityWidget.hpp b/include/ui/QuantityWidget.hpp
deleted file mode 100644
index 67d5f334..00000000
--- a/include/ui/QuantityWidget.hpp
+++ /dev/null
@@ -1,49 +0,0 @@
-#pragma once
-#include "ui/common.hpp"
-
-
-namespace rack {
-
-
-/** A Widget representing a float value */
-struct QuantityWidget : virtual Widget {
-	float value = 0.0;
-	float minValue = 0.0;
-	float maxValue = 1.0;
-	float defaultValue = 0.0;
-	std::string label;
-	/** Include a space character if you want a space after the number, e.g. " Hz" */
-	std::string unit;
-	/** The decimal place to round for displaying values.
-	A precision of 2 will display as "1.00" for example.
-	*/
-	int precision = 2;
-
-	void reset() {
-		setValue(defaultValue);
-	}
-
-	void setValue(float value) {
-		this->value = clampBetween(value, minValue, maxValue);
-		event::Change e;
-		onChange(e);
-	}
-
-	void setLimits(float minValue, float maxValue) {
-		this->minValue = minValue;
-		this->maxValue = maxValue;
-		setValue(value);
-	}
-
-	void setDefaultValue(float defaultValue) {
-		this->defaultValue = defaultValue;
-	}
-
-	/** Generates the display value */
-	std::string getText() {
-		return string::f("%s: %.*f%s", label.c_str(), precision, value, unit.c_str());
-	}
-};
-
-
-} // namespace rack
diff --git a/include/ui/RadioButton.hpp b/include/ui/RadioButton.hpp
index d1ec8edb..cf5c6ebd 100644
--- a/include/ui/RadioButton.hpp
+++ b/include/ui/RadioButton.hpp
@@ -1,36 +1,53 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
-#include "ui/QuantityWidget.hpp"
 
 
 namespace rack {
 
 
-struct RadioButton : OpaqueWidget, QuantityWidget {
+struct RadioButton : OpaqueWidget {
 	BNDwidgetState state = BND_DEFAULT;
+	Quantity *quantity = NULL;
 
 	RadioButton() {
 		box.size.y = BND_WIDGET_HEIGHT;
 	}
 
+	~RadioButton() {
+		if (quantity)
+			delete quantity;
+	}
+
 	void draw(NVGcontext *vg) override {
-		bndRadioButton(vg, 0.0, 0.0, box.size.x, box.size.y, BND_CORNER_NONE, value == 0.0 ? state : BND_ACTIVE, -1, label.c_str());
+		std::string label;
+		if (quantity)
+			label = quantity->getLabel();
+		bndRadioButton(vg, 0.0, 0.0, box.size.x, box.size.y, BND_CORNER_NONE, state, -1, label.c_str());
 	}
 
 	void onEnter(event::Enter &e) override {
-		state = BND_HOVER;
+		if (state != BND_ACTIVE)
+			state = BND_HOVER;
 	}
 
 	void onLeave(event::Leave &e) override {
-		state = BND_DEFAULT;
+		if (state != BND_ACTIVE)
+			state = BND_DEFAULT;
 	}
 
 	void onDragDrop(event::DragDrop &e) override {
 		if (e.origin == this) {
-			if (value)
-				setValue(0.0);
-			else
-				setValue(1.0);
+			if (state == BND_ACTIVE) {
+				state = BND_HOVER;
+				if (quantity)
+					quantity->setMin();
+			}
+			else {
+				state = BND_ACTIVE;
+				if (quantity)
+					quantity->setMax();
+			}
 
 			event::Action eAction;
 			onAction(eAction);
diff --git a/include/ui/Scene.hpp b/include/ui/Scene.hpp
index 0779144a..7eeb4874 100644
--- a/include/ui/Scene.hpp
+++ b/include/ui/Scene.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 
 
diff --git a/include/ui/ScrollWidget.hpp b/include/ui/ScrollWidget.hpp
index 5e45a4aa..2ec82fff 100644
--- a/include/ui/ScrollWidget.hpp
+++ b/include/ui/ScrollWidget.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 #include "event.hpp"
 
diff --git a/include/ui/SequentialLayout.hpp b/include/ui/SequentialLayout.hpp
index 5b0103fc..0322f0bf 100644
--- a/include/ui/SequentialLayout.hpp
+++ b/include/ui/SequentialLayout.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/Widget.hpp"
 #include "ui/common.hpp"
 
 
@@ -6,7 +7,7 @@ namespace rack {
 
 
 /** Positions children in a row/column based on their widths/heights */
-struct SequentialLayout : virtual Widget {
+struct SequentialLayout : VirtualWidget {
 	enum Orientation {
 		HORIZONTAL_ORIENTATION,
 		VERTICAL_ORIENTATION,
diff --git a/include/ui/Slider.hpp b/include/ui/Slider.hpp
index 1be9ceb5..6fec576b 100644
--- a/include/ui/Slider.hpp
+++ b/include/ui/Slider.hpp
@@ -1,6 +1,7 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
+#include "ui/Quantity.hpp"
 #include "ui/common.hpp"
-#include "ui/QuantityWidget.hpp"
 
 
 namespace rack {
@@ -9,16 +10,23 @@ namespace rack {
 static const float SLIDER_SENSITIVITY = 0.001f;
 
 
-struct Slider : OpaqueWidget, QuantityWidget {
+struct Slider : OpaqueWidget {
 	BNDwidgetState state = BND_DEFAULT;
+	Quantity *quantity = NULL;
 
 	Slider() {
 		box.size.y = BND_WIDGET_HEIGHT;
 	}
 
+	~Slider() {
+		if (quantity)
+			delete quantity;
+	}
+
 	void draw(NVGcontext *vg) override {
-		float progress = rescale(value, minValue, maxValue, 0.0, 1.0);
-		bndSlider(vg, 0.0, 0.0, box.size.x, box.size.y, BND_CORNER_NONE, state, progress, getText().c_str(), NULL);
+		float progress = quantity ? quantity->getScaledValue() : 0.f;
+		std::string text = quantity ? quantity->getString() : "";
+		bndSlider(vg, 0.0, 0.0, box.size.x, box.size.y, BND_CORNER_NONE, state, progress, text.c_str(), NULL);
 	}
 
 	void onDragStart(event::DragStart &e) override {
@@ -27,7 +35,9 @@ struct Slider : OpaqueWidget, QuantityWidget {
 	}
 
 	void onDragMove(event::DragMove &e) override {
-		setValue(value + SLIDER_SENSITIVITY * (maxValue - minValue) * e.mouseDelta.x);
+		if (quantity) {
+			quantity->moveScaledValue(SLIDER_SENSITIVITY * e.mouseDelta.x);
+		}
 	}
 
 	void onDragEnd(event::DragEnd &e) override {
@@ -37,7 +47,8 @@ struct Slider : OpaqueWidget, QuantityWidget {
 
 	void onButton(event::Button &e) override {
 		if (e.action == GLFW_PRESS && e.button == GLFW_MOUSE_BUTTON_RIGHT) {
-			setValue(defaultValue);
+			if (quantity)
+				quantity->reset();
 		}
 		e.target = this;
 	}
diff --git a/include/ui/TextField.hpp b/include/ui/TextField.hpp
index ba9c7107..9c814b59 100644
--- a/include/ui/TextField.hpp
+++ b/include/ui/TextField.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 #include "event.hpp"
 
diff --git a/include/ui/Tooltip.hpp b/include/ui/Tooltip.hpp
index 0162c56f..4584d57d 100644
--- a/include/ui/Tooltip.hpp
+++ b/include/ui/Tooltip.hpp
@@ -1,11 +1,12 @@
 #pragma once
+#include "widgets/Widget.hpp"
 #include "ui/common.hpp"
 
 
 namespace rack {
 
 
-struct Tooltip : virtual Widget {
+struct Tooltip : VirtualWidget {
 	std::string text;
 
 	void draw(NVGcontext *vg) override {
diff --git a/include/ui/TooltipOverlay.hpp b/include/ui/TooltipOverlay.hpp
index 6ace069d..02f80a8f 100644
--- a/include/ui/TooltipOverlay.hpp
+++ b/include/ui/TooltipOverlay.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/TransparentWidget.hpp"
 #include "ui/common.hpp"
 
 
diff --git a/include/ui/WindowOverlay.hpp b/include/ui/WindowOverlay.hpp
index ee20cf55..c294b71c 100644
--- a/include/ui/WindowOverlay.hpp
+++ b/include/ui/WindowOverlay.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 
 
diff --git a/include/ui/WindowWidget.hpp b/include/ui/WindowWidget.hpp
index 991a6be4..e8b6befd 100644
--- a/include/ui/WindowWidget.hpp
+++ b/include/ui/WindowWidget.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include "widgets/OpaqueWidget.hpp"
 #include "ui/common.hpp"
 
 
diff --git a/include/ui/common.hpp b/include/ui/common.hpp
index 18a3691a..46183b58 100644
--- a/include/ui/common.hpp
+++ b/include/ui/common.hpp
@@ -1,5 +1,4 @@
 #pragma once
-#include "widgets.hpp"
 #include "blendish.h"
 
 #define CHECKMARK_STRING "✔"
diff --git a/include/widgets/FramebufferWidget.hpp b/include/widgets/FramebufferWidget.hpp
index 4e32c0ed..e83875e1 100644
--- a/include/widgets/FramebufferWidget.hpp
+++ b/include/widgets/FramebufferWidget.hpp
@@ -9,7 +9,7 @@ namespace rack {
 When `dirty` is true, its children will be re-rendered on the next call to step() override.
 Events are not passed to the underlying scene.
 */
-struct FramebufferWidget : virtual Widget {
+struct FramebufferWidget : VirtualWidget {
 	/** Set this to true to re-render the children to the framebuffer the next time it is drawn */
 	bool dirty = true;
 	/** A margin in pixels around the children in the framebuffer
diff --git a/include/widgets/OpaqueWidget.hpp b/include/widgets/OpaqueWidget.hpp
index c5e2783d..49415eec 100644
--- a/include/widgets/OpaqueWidget.hpp
+++ b/include/widgets/OpaqueWidget.hpp
@@ -9,7 +9,7 @@ namespace rack {
 You can of course override the events.
 You may also call OpaqueWidget::on*() from the overridden method to continue recursing/consuming the event.
 */
-struct OpaqueWidget : virtual Widget {
+struct OpaqueWidget : VirtualWidget {
 	void onHover(event::Hover &e) override {
 		Widget::onHover(e);
 		if (!e.target)
diff --git a/include/widgets/SVGWidget.hpp b/include/widgets/SVGWidget.hpp
index f1168201..8cbae659 100644
--- a/include/widgets/SVGWidget.hpp
+++ b/include/widgets/SVGWidget.hpp
@@ -6,7 +6,7 @@ namespace rack {
 
 
 /** Draws an SVG */
-struct SVGWidget : virtual Widget {
+struct SVGWidget : VirtualWidget {
 	std::shared_ptr<SVG> svg;
 
 	/** Sets the box size to the svg image size */
diff --git a/include/widgets/TransformWidget.hpp b/include/widgets/TransformWidget.hpp
index fe7bc60f..deb2ac8d 100644
--- a/include/widgets/TransformWidget.hpp
+++ b/include/widgets/TransformWidget.hpp
@@ -6,7 +6,7 @@ namespace rack {
 
 
 /** Transforms appearance only, not positions of events */
-struct TransformWidget : virtual Widget {
+struct TransformWidget : VirtualWidget {
 	/** The transformation matrix */
 	float transform[6];
 
diff --git a/include/widgets/TransparentWidget.hpp b/include/widgets/TransparentWidget.hpp
index f53910a5..2476268b 100644
--- a/include/widgets/TransparentWidget.hpp
+++ b/include/widgets/TransparentWidget.hpp
@@ -6,7 +6,7 @@ namespace rack {
 
 
 /** Widget that does not respond to events and does not pass events to children */
-struct TransparentWidget : virtual Widget {
+struct TransparentWidget : VirtualWidget {
 	/** Override behavior to do nothing instead. */
 	void onHover(event::Hover &e) override {}
 	void onButton(event::Button &e) override {}
diff --git a/include/widgets/Widget.hpp b/include/widgets/Widget.hpp
index 388c8277..cc50ea95 100644
--- a/include/widgets/Widget.hpp
+++ b/include/widgets/Widget.hpp
@@ -12,7 +12,7 @@ namespace rack {
 
 /** A node in the 2D scene graph
 It is recommended to inherit virtually from Widget instead of directly.
-e.g. `struct MyWidget : virtual Widget {}`
+e.g. `struct MyWidget : VirtualWidget {}`
 */
 struct Widget {
 	/** Stores position and size */
@@ -125,4 +125,10 @@ struct Widget {
 };
 
 
+/** Inherit from this class instead of inheriting from Widget directly.
+Allows multiple inheritance in the class hierarchy.
+*/
+struct VirtualWidget : virtual Widget {};
+
+
 } // namespace rack
diff --git a/include/widgets/ZoomWidget.hpp b/include/widgets/ZoomWidget.hpp
index c6919d92..71beb68e 100644
--- a/include/widgets/ZoomWidget.hpp
+++ b/include/widgets/ZoomWidget.hpp
@@ -5,7 +5,7 @@
 namespace rack {
 
 
-struct ZoomWidget : virtual Widget {
+struct ZoomWidget : VirtualWidget {
 	float zoom = 1.f;
 
 	Vec getRelativeOffset(Vec v, Widget *relative) override {
diff --git a/src/app/AudioWidget.cpp b/src/app/AudioWidget.cpp
index 6e5082be..f6313a7b 100644
--- a/src/app/AudioWidget.cpp
+++ b/src/app/AudioWidget.cpp
@@ -1,4 +1,4 @@
-#include "app.hpp"
+#include "app/AudioWidget.hpp"
 #include "audio.hpp"
 #include "helpers.hpp"
 
diff --git a/src/app/Knob.cpp b/src/app/Knob.cpp
deleted file mode 100644
index 71c2f829..00000000
--- a/src/app/Knob.cpp
+++ /dev/null
@@ -1,52 +0,0 @@
-#include "app.hpp"
-#include "window.hpp"
-#include "engine.hpp"
-// For GLFW_KEY_LEFT_CONTROL, etc.
-#include <GLFW/glfw3.h>
-
-
-namespace rack {
-
-
-static const float KNOB_SENSITIVITY = 0.0015f;
-
-
-Knob::Knob() {
-	smooth = true;
-}
-
-void Knob::onDragStart(event::DragStart &e) {
-	windowCursorLock();
-	dragValue = value;
-	randomizable = false;
-}
-
-void Knob::onDragMove(event::DragMove &e) {
-	float range;
-	if (std::isfinite(minValue) && std::isfinite(maxValue)) {
-		range = maxValue - minValue;
-	}
-	else {
-		// Continuous encoders scale as if their limits are +/-1
-		range = 1.f - (-1.f);
-	}
-	float delta = KNOB_SENSITIVITY * -e.mouseDelta.y * speed * range;
-
-	// Drag slower if Mod is held
-	if (windowIsModPressed())
-		delta /= 16.f;
-	dragValue += delta;
-	dragValue = clampBetween(dragValue, minValue, maxValue);
-	if (snap)
-		setValue(std::round(dragValue));
-	else
-		setValue(dragValue);
-}
-
-void Knob::onDragEnd(event::DragEnd &e) {
-	windowCursorUnlock();
-	randomizable = true;
-}
-
-
-} // namespace rack
diff --git a/src/app/ModuleBrowser.cpp b/src/app/ModuleBrowser.cpp
index bd73d591..bcc8e567 100644
--- a/src/app/ModuleBrowser.cpp
+++ b/src/app/ModuleBrowser.cpp
@@ -44,9 +44,20 @@ static bool isModelMatch(Model *model, std::string search) {
 }
 
 
+struct FavoriteQuantity : Quantity {
+	std::string getString() override {
+		return "★";
+	}
+};
+
+
 struct FavoriteRadioButton : RadioButton {
 	Model *model = NULL;
 
+	FavoriteRadioButton() {
+		quantity = new FavoriteQuantity;
+	}
+
 	void onAction(event::Action &e) override;
 };
 
@@ -111,13 +122,12 @@ struct ModelItem : BrowserListItem {
 
 		FavoriteRadioButton *favoriteButton = createWidget<FavoriteRadioButton>(Vec(8, itemMargin));
 		favoriteButton->box.size.x = 20;
-		favoriteButton->label = "★";
 		addChild(favoriteButton);
 
 		// Set favorite button initial state
 		auto it = sFavoriteModels.find(model);
 		if (it != sFavoriteModels.end())
-			favoriteButton->setValue(1);
+			favoriteButton->quantity->setValue(1);
 		favoriteButton->model = model;
 
 		Label *nameLabel = createWidget<Label>(favoriteButton->box.getTopRight());
@@ -465,7 +475,7 @@ void ClearFilterItem::onAction(event::Action &e) {
 void FavoriteRadioButton::onAction(event::Action &e) {
 	if (!model)
 		return;
-	if (value) {
+	if (quantity->isMax()) {
 		sFavoriteModels.insert(model);
 	}
 	else {
diff --git a/src/app/ModuleWidget.cpp b/src/app/ModuleWidget.cpp
index b40db90c..47769a29 100644
--- a/src/app/ModuleWidget.cpp
+++ b/src/app/ModuleWidget.cpp
@@ -61,18 +61,20 @@ json_t *ModuleWidget::toJson() {
 
 	// plugin
 	json_object_set_new(rootJ, "plugin", json_string(model->plugin->slug.c_str()));
-	// version (of plugin)
+	// version of plugin
 	if (!model->plugin->version.empty())
 		json_object_set_new(rootJ, "version", json_string(model->plugin->version.c_str()));
 	// model
 	json_object_set_new(rootJ, "model", json_string(model->slug.c_str()));
 	// params
-	json_t *paramsJ = json_array();
-	for (ParamWidget *paramWidget : params) {
-		json_t *paramJ = paramWidget->toJson();
-		json_array_append_new(paramsJ, paramJ);
+	if (module) {
+		json_t *paramsJ = json_array();
+		for (Param &param : module->params) {
+			json_t *paramJ = param.toJson();
+			json_array_append_new(paramsJ, paramJ);
+		}
+		json_object_set_new(rootJ, "params", paramsJ);
 	}
-	json_object_set_new(rootJ, "params", paramsJ);
 	// data
 	if (module) {
 		json_t *dataJ = module->toJson();
@@ -126,28 +128,15 @@ void ModuleWidget::fromJson(json_t *rootJ) {
 	size_t i;
 	json_t *paramJ;
 	json_array_foreach(paramsJ, i, paramJ) {
-		if (legacy && legacy <= 1) {
-			// Legacy 1 mode
-			// The index in the array we're iterating is the index of the ParamWidget in the params vector.
-			if (i < params.size()) {
-				// Create upgraded version of param JSON object
-				json_t *newParamJ = json_object();
-				json_object_set(newParamJ, "value", paramJ);
-				params[i]->fromJson(newParamJ);
-				json_decref(newParamJ);
-			}
+		uint32_t paramId = i;
+		// Get paramId
+		json_t *paramIdJ = json_object_get(paramJ, "paramId");
+		if (paramIdJ) {
+			// Legacy v0.6.0 to <v1.0
+			paramId = json_integer_value(paramIdJ);
 		}
-		else {
-			// Get paramId
-			json_t *paramIdJ = json_object_get(paramJ, "paramId");
-			if (!paramIdJ)
-				continue;
-			int paramId = json_integer_value(paramIdJ);
-			// Find ParamWidget(s) with paramId
-			for (ParamWidget *paramWidget : params) {
-				if (paramWidget->paramId == paramId)
-					paramWidget->fromJson(paramJ);
-			}
+		if (paramId < module->params.size()) {
+			module->params[paramId].fromJson(paramJ);
 		}
 	}
 
diff --git a/src/app/MomentarySwitch.cpp b/src/app/MomentarySwitch.cpp
index b34db899..8d4157a1 100644
--- a/src/app/MomentarySwitch.cpp
+++ b/src/app/MomentarySwitch.cpp
@@ -5,11 +5,15 @@ namespace rack {
 
 
 void MomentarySwitch::onDragStart(event::DragStart &e) {
-	setValue(maxValue);
+	if (quantity) {
+		quantity->setMax();
+	}
 }
 
 void MomentarySwitch::onDragEnd(event::DragEnd &e) {
-	setValue(minValue);
+	if (quantity) {
+		quantity->setMin();
+	}
 }
 
 
diff --git a/src/app/ParamWidget.cpp b/src/app/ParamWidget.cpp
index 3574b3cc..f0bfc2fe 100644
--- a/src/app/ParamWidget.cpp
+++ b/src/app/ParamWidget.cpp
@@ -1,4 +1,4 @@
-#include "app.hpp"
+#include "app/ParamWidget.hpp"
 #include "engine.hpp"
 #include "random.hpp"
 
@@ -6,33 +6,28 @@
 namespace rack {
 
 
-json_t *ParamWidget::toJson() {
-	json_t *rootJ = json_object();
-	json_object_set_new(rootJ, "paramId", json_integer(paramId));
-
-	// Infinite params should serialize to 0
-	float v = (std::isfinite(minValue) && std::isfinite(maxValue)) ? value : 0.f;
-	json_object_set_new(rootJ, "value", json_real(v));
-	return rootJ;
-}
-
 void ParamWidget::fromJson(json_t *rootJ) {
 	json_t *valueJ = json_object_get(rootJ, "value");
-	if (valueJ)
-		setValue(json_number_value(valueJ));
+	if (valueJ) {
+		if (quantity)
+			quantity->setValue(json_number_value(valueJ));
+	}
 }
 
 void ParamWidget::reset() {
-	// Infinite params should not be reset
-	if (std::isfinite(minValue) && std::isfinite(maxValue)) {
-		setValue(defaultValue);
+	if (quantity) {
+		// Infinite params should not be reset
+		if (quantity->isBounded())
+			quantity->reset();
 	}
 }
 
 void ParamWidget::randomize() {
-	// Infinite params should not be randomized
-	if (randomizable && std::isfinite(minValue) && std::isfinite(maxValue)) {
-		setValue(rescale(random::uniform(), 0.f, 1.f, minValue, maxValue));
+	if (quantity) {
+		// Infinite params should not be randomized
+		if (quantity->isBounded()) {
+			quantity->setScaledValue(random::uniform());
+		}
 	}
 }
 
@@ -40,20 +35,11 @@ void ParamWidget::onButton(event::Button &e) {
 	OpaqueWidget::onButton(e);
 	if (e.target == this) {
 		if (e.action == GLFW_PRESS && e.button == GLFW_MOUSE_BUTTON_RIGHT) {
-			reset();
+			if (quantity)
+				quantity->reset();
 		}
 	}
 }
 
-void ParamWidget::onChange(event::Change &e) {
-	if (!module)
-		return;
-
-	if (smooth)
-		engineSetParamSmooth(module, paramId, value);
-	else
-		engineSetParam(module, paramId, value);
-}
-
 
 } // namespace rack
diff --git a/src/app/PluginManagerWidget.cpp b/src/app/PluginManagerWidget.cpp
index b4741837..2fa3a9c7 100644
--- a/src/app/PluginManagerWidget.cpp
+++ b/src/app/PluginManagerWidget.cpp
@@ -103,13 +103,28 @@ struct LogOutButton : Button {
 };
 
 
+struct DownloadQuantity : Quantity {
+	float getValue() override {
+		return pluginGetDownloadProgress();
+	}
+
+	float getDisplayValue() override {
+		return getValue() * 100.f;
+	}
+
+	int getPrecision() override {return 0;}
+
+	std::string getLabel() override {
+		return "Downloading " + pluginGetDownloadName();
+	}
+
+	std::string getUnit() override {return "%";}
+};
+
+
 struct DownloadProgressBar : ProgressBar {
-	void step() override {
-		label = "Downloading";
-		std::string name = pluginGetDownloadName();
-		if (name != "")
-			label += " " + name;
-		setValue(100.0 * pluginGetDownloadProgress());
+	DownloadProgressBar() {
+		quantity = new DownloadQuantity;
 	}
 };
 
@@ -187,8 +202,6 @@ PluginManagerWidget::PluginManagerWidget() {
 
 		ProgressBar *downloadProgress = new DownloadProgressBar;
 		downloadProgress->box.size.x = 300;
-		downloadProgress->setLimits(0, 100);
-		downloadProgress->unit = "%";
 		downloadWidget->addChild(downloadProgress);
 
 		// Button *cancelButton = new CancelButton;
diff --git a/src/app/SVGKnob.cpp b/src/app/SVGKnob.cpp
index e76baca3..fffb6eae 100644
--- a/src/app/SVGKnob.cpp
+++ b/src/app/SVGKnob.cpp
@@ -27,14 +27,14 @@ void SVGKnob::setSVG(std::shared_ptr<SVG> svg) {
 
 void SVGKnob::step() {
 	// Re-transform TransformWidget if dirty
-	if (dirty) {
+	if (dirty && quantity) {
 		float angle;
-		if (std::isfinite(minValue) && std::isfinite(maxValue)) {
-			angle = rescale(value, minValue, maxValue, minAngle, maxAngle);
+		if (quantity->isBounded()) {
+			angle = rescale(quantity->getValue(), -1.f, 1.f, minAngle, maxAngle);
+			angle = std::fmod(angle, 2*M_PI);
 		}
 		else {
-			angle = rescale(value, -1.0, 1.0, minAngle, maxAngle);
-			angle = std::fmod(angle, 2*M_PI);
+			angle = rescale(quantity->getScaledValue(), 0.f, 1.f, minAngle, maxAngle);
 		}
 		tw->identity();
 		// Rotate SVG
diff --git a/src/app/SVGSlider.cpp b/src/app/SVGSlider.cpp
index 3579d80c..248558c8 100644
--- a/src/app/SVGSlider.cpp
+++ b/src/app/SVGSlider.cpp
@@ -23,9 +23,12 @@ void SVGSlider::setSVGs(std::shared_ptr<SVG> backgroundSVG, std::shared_ptr<SVG>
 }
 
 void SVGSlider::step() {
-	if (dirty) {
+	if (dirty && quantity) {
 		// Interpolate handle position
-		handle->box.pos = Vec(rescale(value, minValue, maxValue, minHandlePos.x, maxHandlePos.x), rescale(value, minValue, maxValue, minHandlePos.y, maxHandlePos.y));
+		float v = quantity->getScaledValue();
+		handle->box.pos = Vec(
+			rescale(v, 0.f, 1.f, minHandlePos.x, maxHandlePos.x),
+			rescale(v, 0.f, 1.f, minHandlePos.y, maxHandlePos.y));
 	}
 	FramebufferWidget::step();
 }
diff --git a/src/app/SVGSwitch.cpp b/src/app/SVGSwitch.cpp
index 44ce63be..74b02ead 100644
--- a/src/app/SVGSwitch.cpp
+++ b/src/app/SVGSwitch.cpp
@@ -20,10 +20,12 @@ void SVGSwitch::addFrame(std::shared_ptr<SVG> svg) {
 
 void SVGSwitch::onChange(event::Change &e) {
 	assert(frames.size() > 0);
-	float valueScaled = rescale(value, minValue, maxValue, 0, frames.size() - 1);
-	int index = clamp((int) roundf(valueScaled), 0, (int) frames.size() - 1);
-	sw->setSVG(frames[index]);
-	dirty = true;
+	if (quantity) {
+		int index = quantity->getScaledValue() * (frames.size() - 1);
+		index = clamp(index, 0, (int) frames.size() - 1);
+		sw->setSVG(frames[index]);
+		dirty = true;
+	}
 	ParamWidget::onChange(e);
 }
 
diff --git a/src/app/ToggleSwitch.cpp b/src/app/ToggleSwitch.cpp
index 430d5090..982e3d7a 100644
--- a/src/app/ToggleSwitch.cpp
+++ b/src/app/ToggleSwitch.cpp
@@ -7,10 +7,12 @@ namespace rack {
 void ToggleSwitch::onDragStart(event::DragStart &e) {
 	// Cycle through values
 	// e.g. a range of [0.0, 3.0] would have modes 0, 1, 2, and 3.
-	if (value >= maxValue)
-		setValue(minValue);
-	else
-		setValue(value + 1.0);
+	if (quantity) {
+		if (quantity->isMax())
+			quantity->setMin();
+		else
+			quantity->moveValue(1.f);
+	}
 }
 
 
diff --git a/src/app/Toolbar.cpp b/src/app/Toolbar.cpp
index 16dda1a2..dd7a46f2 100644
--- a/src/app/Toolbar.cpp
+++ b/src/app/Toolbar.cpp
@@ -10,12 +10,11 @@ namespace rack {
 
 struct TooltipIconButton : IconButton {
 	Tooltip *tooltip = NULL;
-	std::string tooltipText;
 	void onEnter(event::Enter &e) override {
 		if (!tooltip) {
 			tooltip = new Tooltip;
 			tooltip->box.pos = getAbsoluteOffset(Vec(0, BND_WIDGET_HEIGHT));
-			tooltip->text = tooltipText;
+			tooltip->text = getTooltipText();
 			gRackScene->addChild(tooltip);
 		}
 		IconButton::onEnter(e);
@@ -28,13 +27,14 @@ struct TooltipIconButton : IconButton {
 		}
 		IconButton::onLeave(e);
 	}
+	virtual std::string getTooltipText() {return "";}
 };
 
 struct NewButton : TooltipIconButton {
 	NewButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_146097_cc.svg")));
-		tooltipText = "New patch (" WINDOW_MOD_KEY_NAME "+N)";
 	}
+	std::string getTooltipText() override {return "New patch (" WINDOW_MOD_KEY_NAME "+N)";}
 	void onAction(event::Action &e) override {
 		gRackWidget->reset();
 	}
@@ -43,8 +43,8 @@ struct NewButton : TooltipIconButton {
 struct OpenButton : TooltipIconButton {
 	OpenButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_31859_cc.svg")));
-		tooltipText = "Open patch (" WINDOW_MOD_KEY_NAME "+O)";
 	}
+	std::string getTooltipText() override {return "Open patch (" WINDOW_MOD_KEY_NAME "+O)";}
 	void onAction(event::Action &e) override {
 		gRackWidget->loadDialog();
 	}
@@ -53,8 +53,8 @@ struct OpenButton : TooltipIconButton {
 struct SaveButton : TooltipIconButton {
 	SaveButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_1343816_cc.svg")));
-		tooltipText = "Save patch (" WINDOW_MOD_KEY_NAME "+S)";
 	}
+	std::string getTooltipText() override {return "Save patch (" WINDOW_MOD_KEY_NAME "+S)";}
 	void onAction(event::Action &e) override {
 		gRackWidget->saveDialog();
 	}
@@ -63,8 +63,8 @@ struct SaveButton : TooltipIconButton {
 struct SaveAsButton : TooltipIconButton {
 	SaveAsButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_1343811_cc.svg")));
-		tooltipText = "Save patch as (" WINDOW_MOD_KEY_NAME "+Shift+S)";
 	}
+	std::string getTooltipText() override {return "Save patch as (" WINDOW_MOD_KEY_NAME "+Shift+S)";}
 	void onAction(event::Action &e) override {
 		gRackWidget->saveAsDialog();
 	}
@@ -73,8 +73,8 @@ struct SaveAsButton : TooltipIconButton {
 struct RevertButton : TooltipIconButton {
 	RevertButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_1084369_cc.svg")));
-		tooltipText = "Revert patch";
 	}
+	std::string getTooltipText() override {return "Revert patch";}
 	void onAction(event::Action &e) override {
 		gRackWidget->revert();
 	}
@@ -83,8 +83,8 @@ struct RevertButton : TooltipIconButton {
 struct DisconnectCablesButton : TooltipIconButton {
 	DisconnectCablesButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_1745061_cc.svg")));
-		tooltipText = "Disconnect cables";
 	}
+	std::string getTooltipText() override {return "Disconnect cables";}
 	void onAction(event::Action &e) override {
 		gRackWidget->disconnect();
 	}
@@ -93,8 +93,8 @@ struct DisconnectCablesButton : TooltipIconButton {
 struct PowerMeterButton : TooltipIconButton {
 	PowerMeterButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_305536_cc.svg")));
-		tooltipText = "Toggle power meter (see manual for explanation)";
 	}
+	std::string getTooltipText() override {return "Toggle power meter (see manual for explanation)";}
 	void onAction(event::Action &e) override {
 		gPowerMeter ^= true;
 	}
@@ -117,8 +117,8 @@ struct SampleRateItem : MenuItem {
 struct SampleRateButton : TooltipIconButton {
 	SampleRateButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_1240789_cc.svg")));
-		tooltipText = "Engine sample rate";
 	}
+	std::string getTooltipText() override {return "Engine sample rate";}
 	void onAction(event::Action &e) override {
 		Menu *menu = createMenu();
 		menu->box.pos = getAbsoluteOffset(Vec(0, box.size.y));
@@ -144,18 +144,52 @@ struct SampleRateButton : TooltipIconButton {
 struct RackLockButton : TooltipIconButton {
 	RackLockButton() {
 		setSVG(SVG::load(asset::global("res/icons/noun_468341_cc.svg")));
-		tooltipText = "Lock modules";
 	}
+	std::string getTooltipText() override {return "Lock modules";}
 	void onAction(event::Action &e) override {
 		gRackWidget->lockModules ^= true;
 	}
 };
 
-struct ZoomSlider : Slider {
-	void onAction(event::Action &e) override {
-		Slider::onAction(e);
-		gRackScene->zoomWidget->setZoom(std::round(value) / 100.0);
+struct WireOpacityQuantity : Quantity {
+	void setValue(float value) override {
+		// TODO
+	}
+	float getValue() override {
+		return 0;
+	}
+	float getDefaultValue() override {return 0.5;}
+	std::string getLabel() override {return "Cable opacity";}
+	int getPrecision() override {return 0;}
+};
+
+
+struct WireTensionQuantity : Quantity {
+	void setValue(float value) override {
+		// TODO
+	}
+	float getValue() override {
+		return 0;
+	}
+	float getDefaultValue() override {return 0.5;}
+	std::string getLabel() override {return "Cable tension";}
+	int getPrecision() override {return 0;}
+};
+
+
+struct ZoomQuantity : Quantity {
+	void setValue(float value) override {
+		gRackScene->zoomWidget->setZoom(std::round(value) / 100);
+	}
+	float getValue() override {
+		return gRackScene->zoomWidget->zoom * 100;
 	}
+	float getMinValue() override {return 25;}
+	float getMaxValue() override {return 200;}
+	float getDefaultValue() override {return 100;}
+	std::string getLabel() override {return "Zoom";}
+	std::string getUnit() override {return "%";}
+	int getPrecision() override {return 0;}
 };
 
 
@@ -178,30 +212,22 @@ Toolbar::Toolbar() {
 	layout->addChild(new PowerMeterButton);
 	layout->addChild(new RackLockButton);
 
-	wireOpacitySlider = new Slider;
+	Slider *wireOpacitySlider = new Slider;
+	WireOpacityQuantity *wireOpacityQuantity = new WireOpacityQuantity;
+	wireOpacitySlider->quantity = wireOpacityQuantity;
 	wireOpacitySlider->box.size.x = 150;
-	wireOpacitySlider->label = "Cable opacity";
-	wireOpacitySlider->precision = 0;
-	wireOpacitySlider->unit = "%";
-	wireOpacitySlider->setLimits(0.0, 100.0);
-	wireOpacitySlider->setDefaultValue(50.0);
 	layout->addChild(wireOpacitySlider);
 
-	wireTensionSlider = new Slider;
+	Slider *wireTensionSlider = new Slider;
+	WireTensionQuantity *wireTensionQuantity = new WireTensionQuantity;
+	wireTensionSlider->quantity = wireTensionQuantity;
 	wireTensionSlider->box.size.x = 150;
-	wireTensionSlider->label = "Cable tension";
-	wireTensionSlider->unit = "";
-	wireTensionSlider->setLimits(0.0, 1.0);
-	wireTensionSlider->setDefaultValue(0.5);
 	layout->addChild(wireTensionSlider);
 
-	zoomSlider = new ZoomSlider;
+	Slider *zoomSlider = new Slider;
+	ZoomQuantity *zoomQuantity = new ZoomQuantity;
+	zoomSlider->quantity = zoomQuantity;
 	zoomSlider->box.size.x = 150;
-	zoomSlider->precision = 0;
-	zoomSlider->label = "Zoom";
-	zoomSlider->unit = "%";
-	zoomSlider->setLimits(25.0, 200.0);
-	zoomSlider->setDefaultValue(100.0);
 	layout->addChild(zoomSlider);
 
 	// Kind of hacky, but display the PluginManagerWidget only if the local directory is not the development directory
diff --git a/src/app/WireWidget.cpp b/src/app/WireWidget.cpp
index ebec5340..7dc14aab 100644
--- a/src/app/WireWidget.cpp
+++ b/src/app/WireWidget.cpp
@@ -153,17 +153,17 @@ json_t *WireWidget::toJson() {
 void WireWidget::fromJson(json_t *rootJ) {
 	json_t *colorJ = json_object_get(rootJ, "color");
 	if (colorJ) {
-		// Legacy v0.6.0 and earlier
-		if (json_is_object(colorJ))
-			color = jsonToColor(colorJ);
-		else
+		// v0.6.0 and earlier patches use JSON objects. Just ignore them if so and use the existing wire color.
+		if (json_is_string(colorJ))
 			color = color::fromHexString(json_string_value(colorJ));
 	}
 }
 
 void WireWidget::draw(NVGcontext *vg) {
-	float opacity = gToolbar->wireOpacitySlider->value / 100.0;
-	float tension = gToolbar->wireTensionSlider->value;
+	// float opacity = gToolbar->wireOpacitySlider->value / 100.0;
+	// float tension = gToolbar->wireTensionSlider->value;
+	float opacity = 0.5;
+	float tension = 0.5;
 
 	WireWidget *activeWire = gRackWidget->wireContainer->activeWire;
 	if (activeWire) {
diff --git a/src/engine.cpp b/src/engine.cpp
index 08526aea..a8b9377e 100644
--- a/src/engine.cpp
+++ b/src/engine.cpp
@@ -69,10 +69,27 @@ static int smoothParamId;
 static float smoothValue;
 
 
+json_t *Param::toJson() {
+	json_t *rootJ = json_object();
+
+	// Infinite params should serialize to 0
+	float v = (std::isfinite(minValue) && std::isfinite(maxValue)) ? value : 0.f;
+	json_object_set_new(rootJ, "value", json_real(v));
+
+	return rootJ;
+}
+
+void Param::fromJson(json_t *rootJ) {
+	json_t *valueJ = json_object_get(rootJ, "value");
+	if (valueJ)
+		value = json_number_value(valueJ);
+}
+
+
 float Light::getBrightness() {
 	// LEDs are diodes, so don't allow reverse current.
 	// For some reason, instead of the RMS, the sqrt of RMS looks better
-	return powf(fmaxf(0.f, value), 0.25f);
+	return std::pow(std::fmaxf(0.f, value), 0.25f);
 }
 
 void Light::setBrightnessSmooth(float brightness, float frames) {
diff --git a/src/settings.cpp b/src/settings.cpp
index 5dce8f4d..37c92748 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -31,12 +31,12 @@ static json_t *settingsToJson() {
 	}
 
 	// opacity
-	float opacity = gToolbar->wireOpacitySlider->value;
+	float opacity = gToolbar->wireOpacity;
 	json_t *opacityJ = json_real(opacity);
 	json_object_set_new(rootJ, "wireOpacity", opacityJ);
 
 	// tension
-	float tension = gToolbar->wireTensionSlider->value;
+	float tension = gToolbar->wireTension;
 	json_t *tensionJ = json_real(tension);
 	json_object_set_new(rootJ, "wireTension", tensionJ);
 
@@ -99,18 +99,17 @@ static void settingsFromJson(json_t *rootJ) {
 	// opacity
 	json_t *opacityJ = json_object_get(rootJ, "wireOpacity");
 	if (opacityJ)
-		gToolbar->wireOpacitySlider->value = json_number_value(opacityJ);
+		gToolbar->wireOpacity = json_number_value(opacityJ);
 
 	// tension
 	json_t *tensionJ = json_object_get(rootJ, "wireTension");
 	if (tensionJ)
-		gToolbar->wireTensionSlider->value = json_number_value(tensionJ);
+		gToolbar->wireTension = json_number_value(tensionJ);
 
 	// zoom
 	json_t *zoomJ = json_object_get(rootJ, "zoom");
 	if (zoomJ) {
 		gRackScene->zoomWidget->setZoom(clamp((float) json_number_value(zoomJ), 0.25f, 4.0f));
-		gToolbar->zoomSlider->setValue(json_number_value(zoomJ) * 100.0);
 	}
 
 	// allowCursorLock
diff --git a/src/string.cpp b/src/string.cpp
index a467935f..18a13989 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -63,13 +63,16 @@ std::string filename(std::string path) {
 	return filename;
 }
 
+std::string basename(std::string path) {
+	size_t pos = path.rfind('.');
+	return std::string(path, 0, pos);
+}
+
 std::string extension(std::string path) {
-	const char *ext = strrchr(filename(path).c_str(), '.');
-	if (!ext)
-		return "";
-	return ext + 1;
+	size_t pos = path.rfind('.');
+	return std::string(path, pos);
 }
 
 
-} // namespace network
+} // namespace string
 } // namespace rack
diff --git a/src/system.cpp b/src/system.cpp
index a4c013fa..428c54f8 100644
--- a/src/system.cpp
+++ b/src/system.cpp
@@ -13,8 +13,8 @@ namespace rack {
 namespace system {
 
 
-std::vector<std::string> listEntries(std::string path) {
-	std::vector<std::string> filenames;
+std::list<std::string> listEntries(std::string path) {
+	std::list<std::string> filenames;
 	DIR *dir = opendir(path.c_str());
 	if (dir) {
 		struct dirent *d;