diff --git a/include/app/LightWidget.hpp b/include/app/LightWidget.hpp
index deb29a05..5c6bcac8 100644
--- a/include/app/LightWidget.hpp
+++ b/include/app/LightWidget.hpp
@@ -13,6 +13,7 @@ struct LightWidget : widget::TransparentWidget {
 	NVGcolor borderColor = nvgRGBA(0, 0, 0, 0);
 
 	void draw(const DrawArgs& args) override;
+	virtual void drawBackground(const DrawArgs& args);
 	virtual void drawLight(const DrawArgs& args);
 	virtual void drawHalo(const DrawArgs& args);
 };
diff --git a/include/app/SvgSlider.hpp b/include/app/SvgSlider.hpp
index dce80d4a..95fd3994 100644
--- a/include/app/SvgSlider.hpp
+++ b/include/app/SvgSlider.hpp
@@ -23,6 +23,8 @@ struct SvgSlider : app::SliderKnob {
 	void setBackgroundSvg(std::shared_ptr<Svg> svg);
 	void setHandleSvg(std::shared_ptr<Svg> svg);
 	void onChange(const ChangeEvent& e) override;
+	void setHandlePos(math::Vec minHandlePos, math::Vec maxHandlePos);
+	void setHandlePosCentered(math::Vec minHandlePosCentered, math::Vec maxHandlePosCentered);
 
 	DEPRECATED void setBackgroundSVG(std::shared_ptr<Svg> svg) {
 		setBackgroundSvg(svg);
diff --git a/include/componentlibrary.hpp b/include/componentlibrary.hpp
index 2b9e3f80..e456aa6b 100644
--- a/include/componentlibrary.hpp
+++ b/include/componentlibrary.hpp
@@ -53,7 +53,7 @@ Many of these classes use CRTP (https://en.wikipedia.org/wiki/Curiously_recurrin
 
 To use a red light with its default base class for example, use `RedLight` or `TRedLight<>`. (They are synonymous.)
 
-Use the `Base` template argument if you want a different base class.
+Use the `TBase` template argument if you want a different base class.
 E.g. `RectangleLight<RedLight>`
 
 Although this paradigm might seem confusing at first, it ends up being extremely simple in your plugin code and perfect for "decorating" your classes with appearance traits and behavioral properties.
@@ -62,8 +62,8 @@ For example, need a slider with a green LED? Just use
 	createLightParamCentered<LEDLightSlider<GreenLight>>(...)
 */
 
-template <typename Base = app::ModuleLightWidget>
-struct TSvgLight : Base {
+template <typename TBase = app::ModuleLightWidget>
+struct TSvgLight : TBase {
 	widget::FramebufferWidget* fb;
 	widget::SvgWidget* sw;
 
@@ -83,8 +83,8 @@ struct TSvgLight : Base {
 };
 typedef TSvgLight<> SvgLight;
 
-template <typename Base = app::ModuleLightWidget>
-struct TGrayModuleLightWidget : Base {
+template <typename TBase = app::ModuleLightWidget>
+struct TGrayModuleLightWidget : TBase {
 	TGrayModuleLightWidget() {
 		this->bgColor = nvgRGBA(0x33, 0x33, 0x33, 0xff);
 		this->borderColor = nvgRGBA(0, 0, 0, 53);
@@ -92,40 +92,40 @@ struct TGrayModuleLightWidget : Base {
 };
 typedef TGrayModuleLightWidget<> GrayModuleLightWidget;
 
-template <typename Base = GrayModuleLightWidget>
-struct TRedLight : Base {
+template <typename TBase = GrayModuleLightWidget>
+struct TRedLight : TBase {
 	TRedLight() {
 		this->addBaseColor(SCHEME_RED);
 	}
 };
 typedef TRedLight<> RedLight;
 
-template <typename Base = GrayModuleLightWidget>
-struct TGreenLight : Base {
+template <typename TBase = GrayModuleLightWidget>
+struct TGreenLight : TBase {
 	TGreenLight() {
 		this->addBaseColor(SCHEME_GREEN);
 	}
 };
 typedef TGreenLight<> GreenLight;
 
-template <typename Base = GrayModuleLightWidget>
-struct TYellowLight : Base {
+template <typename TBase = GrayModuleLightWidget>
+struct TYellowLight : TBase {
 	TYellowLight() {
 		this->addBaseColor(SCHEME_YELLOW);
 	}
 };
 typedef TYellowLight<> YellowLight;
 
-template <typename Base = GrayModuleLightWidget>
-struct TBlueLight : Base {
+template <typename TBase = GrayModuleLightWidget>
+struct TBlueLight : TBase {
 	TBlueLight() {
 		this->addBaseColor(SCHEME_BLUE);
 	}
 };
 typedef TBlueLight<> BlueLight;
 
-template <typename Base = GrayModuleLightWidget>
-struct TWhiteLight : Base {
+template <typename TBase = GrayModuleLightWidget>
+struct TWhiteLight : TBase {
 	TWhiteLight() {
 		this->addBaseColor(SCHEME_WHITE);
 	}
@@ -133,8 +133,8 @@ struct TWhiteLight : Base {
 typedef TWhiteLight<> WhiteLight;
 
 /** Reads two adjacent lightIds, so `lightId` and `lightId + 1` must be defined */
-template <typename Base = GrayModuleLightWidget>
-struct TGreenRedLight : Base {
+template <typename TBase = GrayModuleLightWidget>
+struct TGreenRedLight : TBase {
 	TGreenRedLight() {
 		this->addBaseColor(SCHEME_GREEN);
 		this->addBaseColor(SCHEME_RED);
@@ -142,8 +142,8 @@ struct TGreenRedLight : Base {
 };
 typedef TGreenRedLight<> GreenRedLight;
 
-template <typename Base = GrayModuleLightWidget>
-struct TRedGreenBlueLight : Base {
+template <typename TBase = GrayModuleLightWidget>
+struct TRedGreenBlueLight : TBase {
 	TRedGreenBlueLight() {
 		this->addBaseColor(SCHEME_RED);
 		this->addBaseColor(SCHEME_GREEN);
@@ -153,40 +153,42 @@ struct TRedGreenBlueLight : Base {
 typedef TRedGreenBlueLight<> RedGreenBlueLight;
 
 /** Based on the size of 5mm LEDs */
-template <typename Base>
-struct LargeLight : TSvgLight<Base> {
+template <typename TBase>
+struct LargeLight : TSvgLight<TBase> {
 	LargeLight() {
 		this->setSvg(Svg::load(asset::system("res/ComponentLibrary/LargeLight.svg")));
 	}
 };
 
 /** Based on the size of 3mm LEDs */
-template <typename Base>
-struct MediumLight : TSvgLight<Base> {
+template <typename TBase>
+struct MediumLight : TSvgLight<TBase> {
 	MediumLight() {
 		this->setSvg(Svg::load(asset::system("res/ComponentLibrary/MediumLight.svg")));
 	}
 };
 
 /** Based on the size of 2mm LEDs */
-template <typename Base>
-struct SmallLight : TSvgLight<Base> {
+template <typename TBase>
+struct SmallLight : TSvgLight<TBase> {
 	SmallLight() {
 		this->setSvg(Svg::load(asset::system("res/ComponentLibrary/SmallLight.svg")));
 	}
 };
 
 /** Based on the size of 1mm LEDs */
-template <typename Base>
-struct TinyLight : TSvgLight<Base> {
+template <typename TBase>
+struct TinyLight : TSvgLight<TBase> {
 	TinyLight() {
 		this->setSvg(Svg::load(asset::system("res/ComponentLibrary/TinyLight.svg")));
 	}
 };
 
-template <typename Base>
-struct RectangleLight : Base {
-	void drawLight(const widget::Widget::DrawArgs& args) override {
+template <typename TBase>
+struct RectangleLight : TBase {
+	void drawBackground(const widget::Widget::DrawArgs& args) override {
+		// Derived from LightWidget::drawBackground()
+
 		nvgBeginPath(args.vg);
 		nvgRect(args.vg, 0, 0, this->box.size.x, this->box.size.y);
 
@@ -196,12 +198,6 @@ struct RectangleLight : Base {
 			nvgFill(args.vg);
 		}
 
-		// Foreground
-		if (this->color.a > 0.0) {
-			nvgFillColor(args.vg, this->color);
-			nvgFill(args.vg);
-		}
-
 		// Border
 		if (this->borderColor.a > 0.0) {
 			nvgStrokeWidth(args.vg, 0.5);
@@ -209,11 +205,24 @@ struct RectangleLight : Base {
 			nvgStroke(args.vg);
 		}
 	}
+
+	void drawLight(const widget::Widget::DrawArgs& args) override {
+		// Derived from LightWidget::drawLight()
+
+		// Foreground
+		if (this->color.a > 0.0) {
+			nvgBeginPath(args.vg);
+			nvgRect(args.vg, 0, 0, this->box.size.x, this->box.size.y);
+
+			nvgFillColor(args.vg, this->color);
+			nvgFill(args.vg);
+		}
+	}
 };
 
 /** A light for displaying on top of PB61303. Must add a color by subclassing or templating. */
-template <typename Base>
-struct LEDBezelLight : Base {
+template <typename TBase>
+struct LEDBezelLight : TBase {
 	LEDBezelLight() {
 		this->borderColor = color::BLACK_TRANSPARENT;
 		this->bgColor = color::BLACK_TRANSPARENT;
@@ -224,8 +233,8 @@ struct LEDBezelLight : Base {
 /** A light to displayed over PB61303. Must add a color by subclassing or templating.
 Don't add this as a child of the PB61303 itself. Instead, just place it over it as a sibling in the scene graph, offset by mm2px(math::Vec(0.5, 0.5)).
 */
-template <typename Base>
-struct PB61303Light : Base {
+template <typename TBase>
+struct PB61303Light : TBase {
 	PB61303Light() {
 		this->bgColor = color::BLACK_TRANSPARENT;
 		this->box.size = mm2px(math::Vec(9.0, 9.0));
@@ -633,43 +642,52 @@ struct BefacoSlidePot : app::SvgSlider {
 
 struct LEDSlider : app::SvgSlider {
 	LEDSlider() {
-		maxHandlePos = mm2px(math::Vec(0.738, 0.738).plus(math::Vec(2, 0)));
-		minHandlePos = mm2px(math::Vec(0.738, 22.078).plus(math::Vec(2, 0)));
+		// TODO Fix positions
+		setHandlePos(
+			mm2px(math::Vec(0.738, 22.078).plus(math::Vec(2, 0))),
+			mm2px(math::Vec(0.738, 0.738).plus(math::Vec(2, 0)))
+		);
 		setBackgroundSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSlider.svg")));
+		setHandleSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderHandle.svg")));
 	}
 };
 
-/** API is unstable for LEDSlider. Will add a LightWidget later. */
+// TODO Modernize
 struct LEDSliderGreen : LEDSlider {
 	LEDSliderGreen() {
 		setHandleSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderGreenHandle.svg")));
 	}
 };
 
+// TODO Modernize
 struct LEDSliderRed : LEDSlider {
 	LEDSliderRed() {
 		setHandleSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderRedHandle.svg")));
 	}
 };
 
+// TODO Modernize
 struct LEDSliderYellow : LEDSlider {
 	LEDSliderYellow() {
 		setHandleSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderYellowHandle.svg")));
 	}
 };
 
+// TODO Modernize
 struct LEDSliderBlue : LEDSlider {
 	LEDSliderBlue() {
 		setHandleSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderBlueHandle.svg")));
 	}
 };
 
+// TODO Modernize
 struct LEDSliderWhite : LEDSlider {
 	LEDSliderWhite() {
 		setHandleSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderWhiteHandle.svg")));
 	}
 };
 
+// TODO Modernize
 struct LEDSliderHorizontal : app::SvgSlider {
 	LEDSliderHorizontal() {
 		horizontal = true;
@@ -679,32 +697,37 @@ struct LEDSliderHorizontal : app::SvgSlider {
 	}
 };
 
-template <typename Base, typename TLightBase = RedLight>
-struct LightSlider : Base {
+template <typename TBase, typename TLightBase = RedLight>
+struct LightSlider : TBase {
 	app::ModuleLightWidget* light;
 
 	LightSlider() {
-		light = new RectangleLight<TLightBase>;
+		light = new TLightBase;
 		this->addChild(light);
 	}
 
 	void step() override {
-		Base::step();
+		TBase::step();
 		// Move center of light to center of handle
 		light->box.pos = this->handle->box.pos
-				 .plus(this->handle->box.size.div(2))
-				 .minus(light->box.size.div(2));
+			.plus(this->handle->box.size.div(2))
+			.minus(light->box.size.div(2));
 	}
 };
 
-template <typename TLightBase = RedLight>
-struct LEDLightSlider : LightSlider<LEDSlider, TLightBase> {
-	LEDLightSlider() {
-		this->setHandleSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderHandle.svg")));
-		this->light->box.size = mm2px(math::Vec(1.524, 3.276));
+template <typename TBase>
+struct LEDSliderLight : RectangleLight<TSvgLight<TBase>> {
+	LEDSliderLight() {
+		this->setSvg(Svg::load(asset::system("res/ComponentLibrary/LEDSliderLight.svg")));
 	}
 };
 
+template <typename TLightBase = RedLight>
+struct LEDLightSlider : LightSlider<LEDSlider, LEDSliderLight<TLightBase>> {
+	LEDLightSlider() {}
+};
+
+// TODO Modernize
 template <typename TLightBase = RedLight>
 struct LEDLightSliderHorizontal : LightSlider<LEDSliderHorizontal, TLightBase> {
 	LEDLightSliderHorizontal() {
diff --git a/src/app/LightWidget.cpp b/src/app/LightWidget.cpp
index 818ba7d3..2b316aed 100644
--- a/src/app/LightWidget.cpp
+++ b/src/app/LightWidget.cpp
@@ -8,6 +8,22 @@ namespace app {
 
 
 void LightWidget::draw(const DrawArgs& args) {
+	drawBackground(args);
+
+	// Child widgets
+	Widget::draw(args);
+
+	// Dynamic light and halo
+	// Override tint from rack brightness adjustment
+	nvgGlobalAlpha(args.vg, 1.0);
+	// Use the formula `lightColor * (1 - dest) + dest` for blending
+	nvgGlobalCompositeBlendFunc(args.vg, NVG_ONE_MINUS_DST_COLOR, NVG_ONE);
+	drawLight(args);
+	drawHalo(args);
+}
+
+
+void LightWidget::drawBackground(const DrawArgs& args) {
 	float radius = std::min(box.size.x, box.size.y) / 2.0;
 	nvgBeginPath(args.vg);
 	nvgCircle(args.vg, radius, radius, radius);
@@ -24,21 +40,9 @@ void LightWidget::draw(const DrawArgs& args) {
 		nvgStrokeColor(args.vg, borderColor);
 		nvgStroke(args.vg);
 	}
-
-	// Child widgets
-	// TODO Upload new graphics instead of use this hack.
-	// nvgGlobalAlpha(args.vg, 0.5);
-	TransparentWidget::draw(args);
-
-	// Dynamic light and halo
-	// Override tint from rack brightness adjustment
-	nvgGlobalAlpha(args.vg, 1.0);
-	// Use the formula `lightColor * (1 - dest) + dest` for blending
-	nvgGlobalCompositeBlendFunc(args.vg, NVG_ONE_MINUS_DST_COLOR, NVG_ONE);
-	drawLight(args);
-	drawHalo(args);
 }
 
+
 void LightWidget::drawLight(const DrawArgs& args) {
 	// Foreground
 	if (color.a > 0.0) {
@@ -51,6 +55,7 @@ void LightWidget::drawLight(const DrawArgs& args) {
 	}
 }
 
+
 void LightWidget::drawHalo(const DrawArgs& args) {
 	// Don't draw halo if rendering in a framebuffer, e.g. screenshots or Module Browser
 	if (args.fb)
diff --git a/src/app/ModuleLightWidget.cpp b/src/app/ModuleLightWidget.cpp
index 6239d067..57dee576 100644
--- a/src/app/ModuleLightWidget.cpp
+++ b/src/app/ModuleLightWidget.cpp
@@ -54,6 +54,8 @@ ModuleLightWidget::~ModuleLightWidget() {
 engine::Light* ModuleLightWidget::getLight(int colorId) {
 	if (!module)
 		return NULL;
+	if (firstLightId < 0)
+		return NULL;
 	return &module->lights[firstLightId + colorId];
 }
 
@@ -61,6 +63,8 @@ engine::Light* ModuleLightWidget::getLight(int colorId) {
 engine::LightInfo* ModuleLightWidget::getLightInfo() {
 	if (!module)
 		return NULL;
+	if (firstLightId < 0)
+		return NULL;
 	return module->lightInfos[firstLightId];
 }
 
@@ -92,8 +96,8 @@ void ModuleLightWidget::destroyTooltip() {
 void ModuleLightWidget::step() {
 	std::vector<float> brightnesses(baseColors.size());
 
-	if (module) {
-		assert(module->lights.size() >= firstLightId + baseColors.size());
+	if (module && firstLightId >= 0) {
+		assert((int) module->lights.size() >= firstLightId + (int) baseColors.size());
 
 		for (size_t i = 0; i < baseColors.size(); i++) {
 			float b = module->lights[firstLightId + i].getBrightness();
diff --git a/src/app/SvgSlider.cpp b/src/app/SvgSlider.cpp
index c50d0ac1..b4f25b0a 100644
--- a/src/app/SvgSlider.cpp
+++ b/src/app/SvgSlider.cpp
@@ -18,31 +18,45 @@ SvgSlider::SvgSlider() {
 	speed = 2.0;
 }
 
+
 void SvgSlider::setBackgroundSvg(std::shared_ptr<Svg> svg) {
 	background->setSvg(svg);
-	fb->box.size = background->box.size;
 	box.size = background->box.size;
+	fb->box.size = background->box.size;
+	fb->setDirty();
 }
 
+
 void SvgSlider::setHandleSvg(std::shared_ptr<Svg> svg) {
 	handle->setSvg(svg);
-	handle->box.pos = maxHandlePos;
-	fb->dirty = true;
+	handle->box.pos = minHandlePos;
+	fb->setDirty();
 }
 
+
 void SvgSlider::onChange(const ChangeEvent& e) {
 	engine::ParamQuantity* pq = getParamQuantity();
 	if (pq) {
 		// Interpolate handle position
 		float v = math::rescale(pq->getSmoothValue(), pq->getMinValue(), pq->getMaxValue(), 0.f, 1.f);
-		handle->box.pos = math::Vec(
-		                    math::rescale(v, 0.f, 1.f, minHandlePos.x, maxHandlePos.x),
-		                    math::rescale(v, 0.f, 1.f, minHandlePos.y, maxHandlePos.y));
-		fb->dirty = true;
+		handle->box.pos = minHandlePos.crossfade(maxHandlePos, v);
+		fb->setDirty();
 	}
 	ParamWidget::onChange(e);
 }
 
 
+void SvgSlider::setHandlePos(math::Vec minHandlePos, math::Vec maxHandlePos) {
+	this->minHandlePos = minHandlePos;
+	this->maxHandlePos = maxHandlePos;
+}
+
+
+void SvgSlider::setHandlePosCentered(math::Vec minHandlePosCentered, math::Vec maxHandlePosCentered) {
+	this->minHandlePos = minHandlePosCentered.minus(handle->box.size.div(2));
+	this->maxHandlePos = maxHandlePosCentered.minus(handle->box.size.div(2));
+}
+
+
 } // namespace app
 } // namespace rack