diff --git a/dgl/EventHandlers.hpp b/dgl/EventHandlers.hpp
index a460440e..8d553b65 100644
--- a/dgl/EventHandlers.hpp
+++ b/dgl/EventHandlers.hpp
@@ -1,6 +1,6 @@
 /*
  * DISTRHO Plugin Framework (DPF)
- * Copyright (C) 2012-2021 Filipe Coelho <falktx@falktx.com>
+ * Copyright (C) 2012-2022 Filipe Coelho <falktx@falktx.com>
  *
  * Permission to use, copy, modify, and/or distribute this software for any purpose with
  * or without fee is hereby granted, provided that the above copyright notice and this
@@ -168,6 +168,21 @@ private:
 
 // --------------------------------------------------------------------------------------------------------------------
 
+class SliderEventHandler
+{
+public:
+    explicit SliderEventHandler(SubWidget* self);
+    virtual ~SliderEventHandler();
+
+private:
+    struct PrivateData;
+    PrivateData* const pData;
+
+    DISTRHO_LEAK_DETECTOR(SliderEventHandler)
+};
+
+// --------------------------------------------------------------------------------------------------------------------
+
 END_NAMESPACE_DGL
 
 #endif // DGL_EVENT_HANDLERS_HPP_INCLUDED
diff --git a/dgl/Layout.hpp b/dgl/Layout.hpp
new file mode 100644
index 00000000..6a0a964a
--- /dev/null
+++ b/dgl/Layout.hpp
@@ -0,0 +1,64 @@
+/*
+ * DISTRHO Plugin Framework (DPF)
+ * Copyright (C) 2012-2021 Filipe Coelho <falktx@falktx.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any purpose with
+ * or without fee is hereby granted, provided that the above copyright notice and this
+ * permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
+ * TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
+ * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef DGL_LAYOUT_HPP_INCLUDED
+#define DGL_LAYOUT_HPP_INCLUDED
+
+#include "Base.hpp"
+
+#include <list>
+
+START_NAMESPACE_DGL
+
+class SubWidget;
+
+// --------------------------------------------------------------------------------------------------------------------
+
+// NOTE: under development, API to be finalized and documented soon
+
+enum SizeHint {
+    Expanding,
+    Fixed
+};
+
+struct SubWidgetWithSizeHint {
+    SubWidget* widget;
+    SizeHint sizeHint;
+};
+
+template<bool horizontal>
+struct Layout
+{
+    std::list<SubWidgetWithSizeHint> widgets;
+    uint setAbsolutePos(int x, int y, uint padding);
+    void setSize(uint size, uint padding);
+};
+
+typedef Layout<true> HorizontalLayout;
+typedef Layout<false> VerticalLayout;
+
+struct VerticallyStackedHorizontalLayout
+{
+    std::list<HorizontalLayout*> items;
+    void setAbsolutePos(int x, int y, uint padding);
+    void setWidth(uint width, uint padding);
+};
+
+// --------------------------------------------------------------------------------------------------------------------
+
+END_NAMESPACE_DGL
+
+#endif // DGL_LAYOUT_HPP_INCLUDED
diff --git a/dgl/Makefile b/dgl/Makefile
index be92632c..c756bf0d 100644
--- a/dgl/Makefile
+++ b/dgl/Makefile
@@ -34,6 +34,7 @@ OBJS_common = \
 	../build/dgl/Geometry.cpp.o \
 	../build/dgl/ImageBase.cpp.o \
 	../build/dgl/ImageBaseWidgets.cpp.o \
+	../build/dgl/Layout.cpp.o \
 	../build/dgl/Resources.cpp.o \
 	../build/dgl/SubWidget.cpp.o \
 	../build/dgl/SubWidgetPrivateData.cpp.o \
diff --git a/dgl/src/Layout.cpp b/dgl/src/Layout.cpp
new file mode 100644
index 00000000..e924c648
--- /dev/null
+++ b/dgl/src/Layout.cpp
@@ -0,0 +1,89 @@
+/*
+ * DISTRHO Plugin Framework (DPF)
+ * Copyright (C) 2012-2022 Filipe Coelho <falktx@falktx.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any purpose with
+ * or without fee is hereby granted, provided that the above copyright notice and this
+ * permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
+ * TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
+ * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "../Layout.hpp"
+#include "../SubWidget.hpp"
+
+START_NAMESPACE_DGL
+
+// --------------------------------------------------------------------------------------------------------------------
+
+template<> // horizontal
+uint Layout<true>::setAbsolutePos(int x, const int y, const uint padding)
+{
+    uint maxHeight = 0;
+
+    for (SubWidgetWithSizeHint& s : widgets)
+    {
+        maxHeight = std::max(maxHeight, s.widget->getHeight());
+        s.widget->setAbsolutePos(x, y);
+        x += s.widget->getWidth();
+        x += padding;
+    }
+
+    return maxHeight;
+}
+
+template<> // horizontal
+void Layout<true>::setSize(const uint width, const uint padding)
+{
+    uint maxHeight = 0;
+    uint nonFixedWidth = width;
+    uint numDynamiclySizedWidgets = 0;
+
+    for (SubWidgetWithSizeHint& s : widgets)
+    {
+        maxHeight = std::max(maxHeight, s.widget->getHeight());
+
+        if (s.sizeHint == Fixed)
+            nonFixedWidth -= s.widget->getWidth();
+        else
+             ++numDynamiclySizedWidgets;
+    }
+
+    const uint widthPerWidget = numDynamiclySizedWidgets != 0
+                              ? (nonFixedWidth - padding * numDynamiclySizedWidgets) / numDynamiclySizedWidgets
+                              : 0;
+
+    for (SubWidgetWithSizeHint& s : widgets)
+    {
+        if (s.sizeHint != Fixed)
+            s.widget->setSize(widthPerWidget, maxHeight);
+        else
+            s.widget->setHeight(maxHeight);
+    }
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+void VerticallyStackedHorizontalLayout::setAbsolutePos(const int x, int y, const uint padding)
+{
+    for (HorizontalLayout* l : items)
+    {
+        y += l->setAbsolutePos(x, y, padding);
+        y += padding;
+    }
+}
+
+void VerticallyStackedHorizontalLayout::setWidth(const uint width, const uint padding)
+{
+    for (HorizontalLayout* l : items)
+        l->setSize(width, padding);
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+END_NAMESPACE_DGL