diff --git a/tools/sk_app/Window.cpp b/tools/sk_app/Window.cpp
index 436b6b9..6713c4c 100644
--- a/tools/sk_app/Window.cpp
+++ b/tools/sk_app/Window.cpp
@@ -88,6 +88,9 @@
         SkCanvas* canvas = backbuffer->getCanvas();
 
         for (int i = 0; i < fLayers.count(); ++i) {
+            fLayers[i]->onPrePaint();
+        }
+        for (int i = 0; i < fLayers.count(); ++i) {
             fLayers[i]->onPaint(canvas);
         }
 
diff --git a/tools/sk_app/Window.h b/tools/sk_app/Window.h
index 77478b5..b541e24 100644
--- a/tools/sk_app/Window.h
+++ b/tools/sk_app/Window.h
@@ -136,16 +136,19 @@
 
         // return value of 'true' means 'I have handled this event'
         virtual void onBackendCreated() {}
+        virtual void onAttach(Window* window) {}
         virtual bool onChar(SkUnichar c, uint32_t modifiers) { return false; }
         virtual bool onKey(Key key, InputState state, uint32_t modifiers) { return false; }
         virtual bool onMouse(int x, int y, InputState state, uint32_t modifiers) { return false; }
         virtual bool onMouseWheel(float delta, uint32_t modifiers) { return false; }
         virtual bool onTouch(intptr_t owner, InputState state, float x, float y) { return false; }
         virtual void onUIStateChanged(const SkString& stateName, const SkString& stateValue) {}
+        virtual void onPrePaint() {}
         virtual void onPaint(SkCanvas*) {}
     };
 
     void pushLayer(Layer* layer) {
+        layer->onAttach(this);
         fLayers.push(layer);
     }
 
diff --git a/tools/viewer/ImGuiLayer.cpp b/tools/viewer/ImGuiLayer.cpp
new file mode 100644
index 0000000..e55ac9c
--- /dev/null
+++ b/tools/viewer/ImGuiLayer.cpp
@@ -0,0 +1,188 @@
+/*
+* Copyright 2017 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#include "ImGuiLayer.h"
+
+#include "SkCanvas.h"
+#include "SkImage.h"
+#include "SkPixmap.h"
+#include "SkSwizzle.h"
+#include "SkVertices.h"
+
+#include "imgui.h"
+
+#include <stdlib.h>
+#include <map>
+
+using namespace sk_app;
+
+ImGuiLayer::ImGuiLayer() {
+    // ImGui initialization:
+    ImGuiIO& io = ImGui::GetIO();
+
+    // Keymap...
+    io.KeyMap[ImGuiKey_Tab] = (int)Window::Key::kTab;
+    io.KeyMap[ImGuiKey_LeftArrow] = (int)Window::Key::kLeft;
+    io.KeyMap[ImGuiKey_RightArrow] = (int)Window::Key::kRight;
+    io.KeyMap[ImGuiKey_UpArrow] = (int)Window::Key::kUp;
+    io.KeyMap[ImGuiKey_DownArrow] = (int)Window::Key::kDown;
+    io.KeyMap[ImGuiKey_PageUp] = (int)Window::Key::kPageUp;
+    io.KeyMap[ImGuiKey_PageDown] = (int)Window::Key::kPageDown;
+    io.KeyMap[ImGuiKey_Home] = (int)Window::Key::kHome;
+    io.KeyMap[ImGuiKey_End] = (int)Window::Key::kEnd;
+    io.KeyMap[ImGuiKey_Delete] = (int)Window::Key::kDelete;
+    io.KeyMap[ImGuiKey_Backspace] = (int)Window::Key::kBack;
+    io.KeyMap[ImGuiKey_Enter] = (int)Window::Key::kOK;
+    io.KeyMap[ImGuiKey_Escape] = (int)Window::Key::kEscape;
+    io.KeyMap[ImGuiKey_A] = (int)Window::Key::kA;
+    io.KeyMap[ImGuiKey_C] = (int)Window::Key::kC;
+    io.KeyMap[ImGuiKey_V] = (int)Window::Key::kV;
+    io.KeyMap[ImGuiKey_X] = (int)Window::Key::kX;
+    io.KeyMap[ImGuiKey_Y] = (int)Window::Key::kY;
+    io.KeyMap[ImGuiKey_Z] = (int)Window::Key::kZ;
+
+    int w, h;
+    unsigned char* pixels;
+    io.Fonts->GetTexDataAsAlpha8(&pixels, &w, &h);
+    SkImageInfo info = SkImageInfo::MakeA8(w, h);
+    SkPixmap pmap(info, pixels, info.minRowBytes());
+    SkMatrix localMatrix = SkMatrix::MakeScale(1.0f / w, 1.0f / h);
+    auto fontImage = SkImage::MakeFromRaster(pmap, nullptr, nullptr);
+    auto fontShader = fontImage->makeShader(&localMatrix);
+    fFontPaint.setShader(fontShader);
+    fFontPaint.setColor(SK_ColorWHITE);
+    fFontPaint.setFilterQuality(kLow_SkFilterQuality);
+    io.Fonts->TexID = &fFontPaint;
+}
+
+void ImGuiLayer::onAttach(Window* window) {
+    fWindow = window;
+}
+
+bool ImGuiLayer::onMouse(int x, int y, Window::InputState state, uint32_t modifiers) {
+    ImGuiIO& io = ImGui::GetIO();
+    io.MousePos.x = static_cast<float>(x);
+    io.MousePos.y = static_cast<float>(y);
+    if (Window::kDown_InputState == state) {
+        io.MouseDown[0] = true;
+    } else if (Window::kUp_InputState == state) {
+        io.MouseDown[0] = false;
+    }
+    return io.WantCaptureMouse;
+}
+
+bool ImGuiLayer::onMouseWheel(float delta, uint32_t modifiers) {
+    ImGuiIO& io = ImGui::GetIO();
+    io.MouseWheel += delta;
+    return true;
+}
+
+void ImGuiLayer::skiaWidget(const ImVec2& size, SkiaWidgetFunc func) {
+    intptr_t funcIndex = fSkiaWidgetFuncs.count();
+    fSkiaWidgetFuncs.push_back(func);
+    ImGui::Image((ImTextureID)funcIndex, size);
+}
+
+void ImGuiLayer::onPrePaint() {
+    // Update ImGui input
+    ImGuiIO& io = ImGui::GetIO();
+    io.DeltaTime = 1.0f / 60.0f;
+    io.DisplaySize.x = static_cast<float>(fWindow->width());
+    io.DisplaySize.y = static_cast<float>(fWindow->height());
+
+    io.KeyAlt = io.KeysDown[static_cast<int>(Window::Key::kOption)];
+    io.KeyCtrl = io.KeysDown[static_cast<int>(Window::Key::kCtrl)];
+    io.KeyShift = io.KeysDown[static_cast<int>(Window::Key::kShift)];
+
+    ImGui::NewFrame();
+}
+
+void ImGuiLayer::onPaint(SkCanvas* canvas) {
+    // This causes ImGui to rebuild vertex/index data based on all immediate-mode commands
+    // (widgets, etc...) that have been issued
+    ImGui::Render();
+
+    // Then we fetch the most recent data, and convert it so we can render with Skia
+    const ImDrawData* drawData = ImGui::GetDrawData();
+    SkTDArray<SkPoint> pos;
+    SkTDArray<SkPoint> uv;
+    SkTDArray<SkColor> color;
+
+    for (int i = 0; i < drawData->CmdListsCount; ++i) {
+        const ImDrawList* drawList = drawData->CmdLists[i];
+
+        // De-interleave all vertex data (sigh), convert to Skia types
+        pos.rewind(); uv.rewind(); color.rewind();
+        for (int i = 0; i < drawList->VtxBuffer.size(); ++i) {
+            const ImDrawVert& vert = drawList->VtxBuffer[i];
+            pos.push(SkPoint::Make(vert.pos.x, vert.pos.y));
+            uv.push(SkPoint::Make(vert.uv.x, vert.uv.y));
+            color.push(vert.col);
+        }
+        // ImGui colors are RGBA
+        SkSwapRB(color.begin(), color.begin(), color.count());
+
+        int indexOffset = 0;
+
+        // Draw everything with canvas.drawVertices...
+        for (int j = 0; j < drawList->CmdBuffer.size(); ++j) {
+            const ImDrawCmd* drawCmd = &drawList->CmdBuffer[j];
+
+            SkAutoCanvasRestore acr(canvas, true);
+
+            // TODO: Find min/max index for each draw, so we know how many vertices (sigh)
+            if (drawCmd->UserCallback) {
+                drawCmd->UserCallback(drawList, drawCmd);
+            } else {
+                intptr_t idIndex = (intptr_t)drawCmd->TextureId;
+                if (idIndex < fSkiaWidgetFuncs.count()) {
+                    // Small image IDs are actually indices into a list of callbacks. We directly
+                    // examing the vertex data to deduce the image rectangle, then reconfigure the
+                    // canvas to be clipped and translated so that the callback code gets to use
+                    // Skia to render a widget in the middle of an ImGui panel.
+                    ImDrawIdx rectIndex = drawList->IdxBuffer[indexOffset];
+                    SkPoint tl = pos[rectIndex], br = pos[rectIndex + 2];
+                    canvas->clipRect(SkRect::MakeLTRB(tl.fX, tl.fY, br.fX, br.fY));
+                    canvas->translate(tl.fX, tl.fY);
+                    fSkiaWidgetFuncs[idIndex](canvas);
+                } else {
+                    SkPaint* paint = static_cast<SkPaint*>(drawCmd->TextureId);
+                    SkASSERT(paint);
+
+                    canvas->clipRect(SkRect::MakeLTRB(drawCmd->ClipRect.x, drawCmd->ClipRect.y,
+                                                      drawCmd->ClipRect.z, drawCmd->ClipRect.w));
+                    auto vertices = SkVertices::MakeCopy(SkVertices::kTriangles_VertexMode,
+                                                         drawList->VtxBuffer.size(),
+                                                         pos.begin(), uv.begin(), color.begin(),
+                                                         drawCmd->ElemCount,
+                                                         drawList->IdxBuffer.begin() + indexOffset);
+                    canvas->drawVertices(vertices, SkBlendMode::kModulate, *paint);
+                    indexOffset += drawCmd->ElemCount;
+                }
+            }
+        }
+    }
+
+    fSkiaWidgetFuncs.reset();
+}
+
+bool ImGuiLayer::onKey(sk_app::Window::Key key, sk_app::Window::InputState state, uint32_t modifiers) {
+    ImGuiIO& io = ImGui::GetIO();
+    io.KeysDown[static_cast<int>(key)] = (Window::kDown_InputState == state);
+    return io.WantCaptureKeyboard;
+}
+
+bool ImGuiLayer::onChar(SkUnichar c, uint32_t modifiers) {
+    ImGuiIO& io = ImGui::GetIO();
+    if (io.WantTextInput) {
+        if (c > 0 && c < 0x10000) {
+            io.AddInputCharacter(c);
+        }
+        return true;
+    }
+    return false;
+}
diff --git a/tools/viewer/ImGuiLayer.h b/tools/viewer/ImGuiLayer.h
new file mode 100644
index 0000000..1cefcd4
--- /dev/null
+++ b/tools/viewer/ImGuiLayer.h
@@ -0,0 +1,37 @@
+/*
+* Copyright 2017 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#ifndef ImGuiLayer_DEFINED
+#define ImGuiLayer_DEFINED
+
+#include "SkPaint.h"
+#include "SkTArray.h"
+#include "sk_app/Window.h"
+#include "imgui.h"
+
+class ImGuiLayer : public sk_app::Window::Layer {
+public:
+    ImGuiLayer();
+
+    typedef std::function<void(SkCanvas*)> SkiaWidgetFunc;
+    void skiaWidget(const ImVec2& size, SkiaWidgetFunc func);
+
+    void onAttach(sk_app::Window* window) override;
+    void onPrePaint() override;
+    void onPaint(SkCanvas* canvas) override;
+    bool onMouse(int x, int y, sk_app::Window::InputState state, uint32_t modifiers) override;
+    bool onMouseWheel(float delta, uint32_t modifiers) override;
+    bool onKey(sk_app::Window::Key key, sk_app::Window::InputState state, uint32_t modifiers) override;
+    bool onChar(SkUnichar c, uint32_t modifiers) override;
+
+private:
+    sk_app::Window* fWindow;
+    SkPaint fFontPaint;
+    SkTArray<SkiaWidgetFunc> fSkiaWidgetFuncs;
+};
+
+#endif
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index a1b7baa..c184eec 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -251,6 +251,7 @@
     // register callbacks
     fCommands.attach(fWindow);
     fWindow->pushLayer(this);
+    fWindow->pushLayer(&fImGuiLayer);
 
     // add key-bindings
     fCommands.addCommand(' ', "GUI", "Toggle Debug GUI", [this]() {
@@ -412,45 +413,6 @@
 
     fAnimTimer.run();
 
-    // ImGui initialization:
-    ImGuiIO& io = ImGui::GetIO();
-    io.DisplaySize.x = static_cast<float>(fWindow->width());
-    io.DisplaySize.y = static_cast<float>(fWindow->height());
-
-    // Keymap...
-    io.KeyMap[ImGuiKey_Tab] = (int)Window::Key::kTab;
-    io.KeyMap[ImGuiKey_LeftArrow] = (int)Window::Key::kLeft;
-    io.KeyMap[ImGuiKey_RightArrow] = (int)Window::Key::kRight;
-    io.KeyMap[ImGuiKey_UpArrow] = (int)Window::Key::kUp;
-    io.KeyMap[ImGuiKey_DownArrow] = (int)Window::Key::kDown;
-    io.KeyMap[ImGuiKey_PageUp] = (int)Window::Key::kPageUp;
-    io.KeyMap[ImGuiKey_PageDown] = (int)Window::Key::kPageDown;
-    io.KeyMap[ImGuiKey_Home] = (int)Window::Key::kHome;
-    io.KeyMap[ImGuiKey_End] = (int)Window::Key::kEnd;
-    io.KeyMap[ImGuiKey_Delete] = (int)Window::Key::kDelete;
-    io.KeyMap[ImGuiKey_Backspace] = (int)Window::Key::kBack;
-    io.KeyMap[ImGuiKey_Enter] = (int)Window::Key::kOK;
-    io.KeyMap[ImGuiKey_Escape] = (int)Window::Key::kEscape;
-    io.KeyMap[ImGuiKey_A] = (int)Window::Key::kA;
-    io.KeyMap[ImGuiKey_C] = (int)Window::Key::kC;
-    io.KeyMap[ImGuiKey_V] = (int)Window::Key::kV;
-    io.KeyMap[ImGuiKey_X] = (int)Window::Key::kX;
-    io.KeyMap[ImGuiKey_Y] = (int)Window::Key::kY;
-    io.KeyMap[ImGuiKey_Z] = (int)Window::Key::kZ;
-
-    int w, h;
-    unsigned char* pixels;
-    io.Fonts->GetTexDataAsAlpha8(&pixels, &w, &h);
-    SkImageInfo info = SkImageInfo::MakeA8(w, h);
-    SkPixmap pmap(info, pixels, info.minRowBytes());
-    SkMatrix localMatrix = SkMatrix::MakeScale(1.0f / w, 1.0f / h);
-    auto fontImage = SkImage::MakeFromRaster(pmap, nullptr, nullptr);
-    auto fontShader = fontImage->makeShader(&localMatrix);
-    fImGuiFontPaint.setShader(fontShader);
-    fImGuiFontPaint.setColor(SK_ColorWHITE);
-    fImGuiFontPaint.setFilterQuality(kLow_SkFilterQuality);
-    io.Fonts->TexID = &fImGuiFontPaint;
-
     auto gamutImage = GetResourceAsImage("images/gamut.png");
     if (gamutImage) {
         fImGuiGamutPaint.setShader(gamutImage->makeShader());
@@ -729,6 +691,8 @@
     // re-register callbacks
     fCommands.attach(fWindow);
     fWindow->pushLayer(this);
+    fWindow->pushLayer(&fImGuiLayer);
+
     // Don't allow the window to re-attach. If we're in MSAA mode, the params we grabbed above
     // will still include our correct sample count. But the re-created fWindow will lose that
     // information. On Windows, we need to re-create the window when changing sample count,
@@ -876,18 +840,6 @@
 }
 
 void Viewer::onPaint(SkCanvas* canvas) {
-    // Update ImGui input
-    ImGuiIO& io = ImGui::GetIO();
-    io.DeltaTime = 1.0f / 60.0f;
-    io.DisplaySize.x = static_cast<float>(fWindow->width());
-    io.DisplaySize.y = static_cast<float>(fWindow->height());
-
-    io.KeyAlt = io.KeysDown[static_cast<int>(Window::Key::kOption)];
-    io.KeyCtrl = io.KeysDown[static_cast<int>(Window::Key::kCtrl)];
-    io.KeyShift = io.KeysDown[static_cast<int>(Window::Key::kShift)];
-
-    ImGui::NewFrame();
-
     this->drawSlide(canvas);
 
     // Advance our timing bookkeeping
@@ -904,7 +856,7 @@
     }
     fCommands.drawHelp(canvas);
 
-    this->drawImGui(canvas);
+    this->drawImGui();
 
     // Update the FPS
     this->updateUIState();
@@ -935,45 +887,27 @@
 }
 
 bool Viewer::onMouse(int x, int y, Window::InputState state, uint32_t modifiers) {
-    ImGuiIO& io = ImGui::GetIO();
-    io.MousePos.x = static_cast<float>(x);
-    io.MousePos.y = static_cast<float>(y);
-    if (Window::kDown_InputState == state) {
-        io.MouseDown[0] = true;
-    } else if (Window::kUp_InputState == state) {
-        io.MouseDown[0] = false;
-    }
-    if (io.WantCaptureMouse) {
-        return true;
-    } else {
-        if (!fSlides[fCurrentSlide]->onMouse(x, y, state, modifiers)) {
-            if (GestureDevice::kTouch == fGestureDevice) {
-                return false;
-            }
-            switch (state) {
-                case Window::kUp_InputState: {
-                    fGesture.touchEnd(nullptr);
-                    break;
-                }
-                case Window::kDown_InputState: {
-                    fGesture.touchBegin(nullptr, x, y);
-                    break;
-                }
-                case Window::kMove_InputState: {
-                    fGesture.touchMoved(nullptr, x, y);
-                    break;
-                }
-            }
-            fGestureDevice = fGesture.isBeingTouched() ? GestureDevice::kMouse : GestureDevice::kNone;
+    if (!fSlides[fCurrentSlide]->onMouse(x, y, state, modifiers)) {
+        if (GestureDevice::kTouch == fGestureDevice) {
+            return false;
         }
-        fWindow->inval();
-        return true;
+        switch (state) {
+            case Window::kUp_InputState: {
+                fGesture.touchEnd(nullptr);
+                break;
+            }
+            case Window::kDown_InputState: {
+                fGesture.touchBegin(nullptr, x, y);
+                break;
+            }
+            case Window::kMove_InputState: {
+                fGesture.touchMoved(nullptr, x, y);
+                break;
+            }
+        }
+        fGestureDevice = fGesture.isBeingTouched() ? GestureDevice::kMouse : GestureDevice::kNone;
     }
-}
-
-bool Viewer::onMouseWheel(float delta, uint32_t modifiers) {
-    ImGuiIO& io = ImGui::GetIO();
-    io.MouseWheel += delta;
+    fWindow->inval();
     return true;
 }
 
@@ -1133,16 +1067,7 @@
     ImGui::SetCursorPos(endPos);
 }
 
-typedef std::function<void(SkCanvas*)> CustomGuiPainter;
-static SkTArray<CustomGuiPainter> gCustomGuiPainters;
-
-static void ImGui_Skia_Callback(const ImVec2& size, CustomGuiPainter painter) {
-    intptr_t painterIndex = gCustomGuiPainters.count();
-    gCustomGuiPainters.push_back(painter);
-    ImGui::Image((ImTextureID)painterIndex, size);
-}
-
-void Viewer::drawImGui(SkCanvas* canvas) {
+void Viewer::drawImGui() {
     // Support drawing the ImGui demo window. Superfluous, but gives a good idea of what's possible
     if (fShowImGuiTestWindow) {
         ImGui::ShowTestWindow(&fShowImGuiTestWindow);
@@ -1351,7 +1276,7 @@
                             SkGetPackedB32(pixel), SkGetPackedA32(pixel));
             }
 
-            ImGui_Skia_Callback(avail, [=](SkCanvas* c) {
+            fImGuiLayer.skiaWidget(avail, [=](SkCanvas* c) {
                 // Translate so the region of the image that's under the mouse cursor is centered
                 // in the zoom canvas:
                 c->scale(zoomFactor, zoomFactor);
@@ -1367,73 +1292,6 @@
 
         ImGui::End();
     }
-
-    // This causes ImGui to rebuild vertex/index data based on all immediate-mode commands
-    // (widgets, etc...) that have been issued
-    ImGui::Render();
-
-    // Then we fetch the most recent data, and convert it so we can render with Skia
-    const ImDrawData* drawData = ImGui::GetDrawData();
-    SkTDArray<SkPoint> pos;
-    SkTDArray<SkPoint> uv;
-    SkTDArray<SkColor> color;
-
-    for (int i = 0; i < drawData->CmdListsCount; ++i) {
-        const ImDrawList* drawList = drawData->CmdLists[i];
-
-        // De-interleave all vertex data (sigh), convert to Skia types
-        pos.rewind(); uv.rewind(); color.rewind();
-        for (int i = 0; i < drawList->VtxBuffer.size(); ++i) {
-            const ImDrawVert& vert = drawList->VtxBuffer[i];
-            pos.push(SkPoint::Make(vert.pos.x, vert.pos.y));
-            uv.push(SkPoint::Make(vert.uv.x, vert.uv.y));
-            color.push(vert.col);
-        }
-        // ImGui colors are RGBA
-        SkSwapRB(color.begin(), color.begin(), color.count());
-
-        int indexOffset = 0;
-
-        // Draw everything with canvas.drawVertices...
-        for (int j = 0; j < drawList->CmdBuffer.size(); ++j) {
-            const ImDrawCmd* drawCmd = &drawList->CmdBuffer[j];
-
-            SkAutoCanvasRestore acr(canvas, true);
-
-            // TODO: Find min/max index for each draw, so we know how many vertices (sigh)
-            if (drawCmd->UserCallback) {
-                drawCmd->UserCallback(drawList, drawCmd);
-            } else {
-                intptr_t idIndex = (intptr_t)drawCmd->TextureId;
-                if (idIndex < gCustomGuiPainters.count()) {
-                    // Small image IDs are actually indices into a list of callbacks. We directly
-                    // examing the vertex data to deduce the image rectangle, then reconfigure the
-                    // canvas to be clipped and translated so that the callback code gets to use
-                    // Skia to render a widget in the middle of an ImGui panel.
-                    ImDrawIdx rectIndex = drawList->IdxBuffer[indexOffset];
-                    SkPoint tl = pos[rectIndex], br = pos[rectIndex + 2];
-                    canvas->clipRect(SkRect::MakeLTRB(tl.fX, tl.fY, br.fX, br.fY));
-                    canvas->translate(tl.fX, tl.fY);
-                    gCustomGuiPainters[idIndex](canvas);
-                } else {
-                    SkPaint* paint = static_cast<SkPaint*>(drawCmd->TextureId);
-                    SkASSERT(paint);
-
-                    canvas->clipRect(SkRect::MakeLTRB(drawCmd->ClipRect.x, drawCmd->ClipRect.y,
-                                                      drawCmd->ClipRect.z, drawCmd->ClipRect.w));
-                    auto vertices = SkVertices::MakeCopy(SkVertices::kTriangles_VertexMode,
-                                                         drawList->VtxBuffer.size(),
-                                                         pos.begin(), uv.begin(), color.begin(),
-                                                         drawCmd->ElemCount,
-                                                         drawList->IdxBuffer.begin() + indexOffset);
-                    canvas->drawVertices(vertices, SkBlendMode::kModulate, *paint);
-                    indexOffset += drawCmd->ElemCount;
-                }
-            }
-        }
-    }
-
-    gCustomGuiPainters.reset();
 }
 
 void Viewer::onIdle() {
@@ -1626,24 +1484,11 @@
 }
 
 bool Viewer::onKey(sk_app::Window::Key key, sk_app::Window::InputState state, uint32_t modifiers) {
-    ImGuiIO& io = ImGui::GetIO();
-    io.KeysDown[static_cast<int>(key)] = (Window::kDown_InputState == state);
-
-    if (io.WantCaptureKeyboard) {
-        return true;
-    } else {
-        return fCommands.onKey(key, state, modifiers);
-    }
+    return fCommands.onKey(key, state, modifiers);
 }
 
 bool Viewer::onChar(SkUnichar c, uint32_t modifiers) {
-    ImGuiIO& io = ImGui::GetIO();
-    if (io.WantTextInput) {
-        if (c > 0 && c < 0x10000) {
-            io.AddInputCharacter(c);
-        }
-        return true;
-    } else if (fSlides[fCurrentSlide]->onChar(c)) {
+    if (fSlides[fCurrentSlide]->onChar(c)) {
         fWindow->inval();
         return true;
     } else {
diff --git a/tools/viewer/Viewer.h b/tools/viewer/Viewer.h
index 1f5d1c5..2ab3de5 100644
--- a/tools/viewer/Viewer.h
+++ b/tools/viewer/Viewer.h
@@ -12,6 +12,7 @@
 #include "sk_app/CommandSet.h"
 #include "sk_app/Window.h"
 #include "gm.h"
+#include "ImGuiLayer.h"
 #include "SkAnimTimer.h"
 #include "SkExecutor.h"
 #include "SkJSONCPP.h"
@@ -31,7 +32,6 @@
     void onPaint(SkCanvas* canvas) override;
     bool onTouch(intptr_t owner, sk_app::Window::InputState state, float x, float y) override;
     bool onMouse(int x, int y, sk_app::Window::InputState state, uint32_t modifiers) override;
-    bool onMouseWheel(float delta, uint32_t modifiers) override;
     void onUIStateChanged(const SkString& stateName, const SkString& stateValue) override;
     bool onKey(sk_app::Window::Key key, sk_app::Window::InputState state, uint32_t modifiers) override;
     bool onChar(SkUnichar c, uint32_t modifiers) override;
@@ -57,7 +57,7 @@
 
     void drawSlide(SkCanvas* canvs);
     void drawStats(SkCanvas* canvas);
-    void drawImGui(SkCanvas* canvas);
+    void drawImGui();
 
     void changeZoomLevel(float delta);
     SkMatrix computeMatrix();
@@ -85,7 +85,7 @@
 
     bool                   fSaveToSKP;
 
-    SkPaint                fImGuiFontPaint;
+    ImGuiLayer             fImGuiLayer;
     SkPaint                fImGuiGamutPaint;
     bool                   fShowImGuiDebugWindow;
     bool                   fShowSlidePicker;