diff --git a/bin/toucan-edit/App.cpp b/bin/toucan-edit/App.cpp
index 7dc7236..0dc8407 100644
--- a/bin/toucan-edit/App.cpp
+++ b/bin/toucan-edit/App.cpp
@@ -4,7 +4,10 @@
 
 #include "App.h"
 
+#include "DocumentsModel.h"
+#include "TimeUnitsModel.h"
 #include "Timeline.h"
+#include "Window.h"
 
 #include <dtk/ui/FileBrowser.h>
 #include <dtk/ui/MessageDialog.h>
diff --git a/bin/toucan-edit/App.h b/bin/toucan-edit/App.h
index e3d3701..bc9ba21 100644
--- a/bin/toucan-edit/App.h
+++ b/bin/toucan-edit/App.h
@@ -4,14 +4,16 @@
 
 #pragma once
 
-#include "DocumentsModel.h"
-#include "TimeUnitsModel.h"
-#include "Window.h"
+#include <toucan/ImageEffectHost.h>
 
 #include <dtk/ui/App.h>
 
 namespace toucan
 {
+    class DocumentsModel;
+    class TimeUnitsModel;
+    class Window;
+
     class App : public dtk::App
     {
     protected:
diff --git a/bin/toucan-edit/BottomBar.cpp b/bin/toucan-edit/BottomBar.cpp
index c5f7f5e..5ee6941 100644
--- a/bin/toucan-edit/BottomBar.cpp
+++ b/bin/toucan-edit/BottomBar.cpp
@@ -5,6 +5,8 @@
 #include "BottomBar.h"
 
 #include "App.h"
+#include "DocumentsModel.h"
+#include "TimeWidgets.h"
 
 namespace toucan
 {
diff --git a/bin/toucan-edit/BottomBar.h b/bin/toucan-edit/BottomBar.h
index 3a3cb65..eeb2de5 100644
--- a/bin/toucan-edit/BottomBar.h
+++ b/bin/toucan-edit/BottomBar.h
@@ -4,7 +4,7 @@
 
 #pragma once
 
-#include "TimeWidgets.h"
+#include "PlaybackModel.h"
 
 #include <dtk/ui/RowLayout.h>
 #include <dtk/ui/ToolButton.h>
@@ -13,6 +13,10 @@ namespace toucan
 {
     class App;
     class Document;
+    class FrameButtons;
+    class PlaybackButtons;
+    class TimeEdit;
+    class TimeLabel;
 
     class BottomBar : public dtk::IWidget
     {
diff --git a/bin/toucan-edit/ClipWidget.cpp b/bin/toucan-edit/ClipWidget.cpp
index 7400e9f..6a87e62 100644
--- a/bin/toucan-edit/ClipWidget.cpp
+++ b/bin/toucan-edit/ClipWidget.cpp
@@ -4,6 +4,8 @@
 
 #include "ClipWidget.h"
 
+#include "Clip.h"
+
 #include <dtk/ui/DrawUtil.h>
 #include <dtk/core/RenderUtil.h>
 
diff --git a/bin/toucan-edit/ClipWidget.h b/bin/toucan-edit/ClipWidget.h
index f74ea3b..6069e7a 100644
--- a/bin/toucan-edit/ClipWidget.h
+++ b/bin/toucan-edit/ClipWidget.h
@@ -4,11 +4,12 @@
 
 #pragma once
 
-#include "Clip.h"
 #include "IItemWidget.h"
 
 namespace toucan
 {
+    class Clip;
+
     class ClipWidget : public IItemWidget
     {
     protected:
diff --git a/bin/toucan-edit/Document.cpp b/bin/toucan-edit/Document.cpp
index 8b6db19..0f15146 100644
--- a/bin/toucan-edit/Document.cpp
+++ b/bin/toucan-edit/Document.cpp
@@ -4,8 +4,10 @@
 
 #include "Document.h"
 
+#include "ImageGraph.h"
 #include "PlaybackModel.h"
 #include "SelectionModel.h"
+#include "Timeline.h"
 #include "ThumbnailGenerator.h"
 #include "ViewModel.h"
 
diff --git a/bin/toucan-edit/Document.h b/bin/toucan-edit/Document.h
index 6a16890..2a16e2d 100644
--- a/bin/toucan-edit/Document.h
+++ b/bin/toucan-edit/Document.h
@@ -4,9 +4,6 @@
 
 #pragma once
 
-#include "ImageGraph.h"
-#include "Timeline.h"
-
 #include <toucan/ImageEffectHost.h>
 
 #include <dtk/core/Context.h>
@@ -17,8 +14,10 @@
 
 namespace toucan
 {
+    class ImageGraph;
     class PlaybackModel;
     class SelectionModel;
+    class Timeline;
     class ThumbnailGenerator;
     class ViewModel;
 
diff --git a/bin/toucan-edit/Gap.h b/bin/toucan-edit/Gap.h
index 9b14aa0..921c59c 100644
--- a/bin/toucan-edit/Gap.h
+++ b/bin/toucan-edit/Gap.h
@@ -6,8 +6,6 @@
 
 #include "IItem.h"
 
-#include <vector>
-
 namespace toucan
 {
     class Gap : public IItem
diff --git a/bin/toucan-edit/GapWidget.cpp b/bin/toucan-edit/GapWidget.cpp
index dcf63f2..2fcbad3 100644
--- a/bin/toucan-edit/GapWidget.cpp
+++ b/bin/toucan-edit/GapWidget.cpp
@@ -4,6 +4,8 @@
 
 #include "GapWidget.h"
 
+#include "Gap.h"
+
 #include <dtk/ui/DrawUtil.h>
 #include <dtk/core/Random.h>
 #include <dtk/core/RenderUtil.h>
diff --git a/bin/toucan-edit/GapWidget.h b/bin/toucan-edit/GapWidget.h
index 20de765..162b82f 100644
--- a/bin/toucan-edit/GapWidget.h
+++ b/bin/toucan-edit/GapWidget.h
@@ -4,11 +4,12 @@
 
 #pragma once
 
-#include "Gap.h"
 #include "IItemWidget.h"
 
 namespace toucan
 {
+    class Gap;
+
     class GapWidget : public IItemWidget
     {
     protected:
diff --git a/bin/toucan-edit/MenuBar.cpp b/bin/toucan-edit/MenuBar.cpp
index 6a1796d..471299b 100644
--- a/bin/toucan-edit/MenuBar.cpp
+++ b/bin/toucan-edit/MenuBar.cpp
@@ -5,8 +5,10 @@
 #include "MenuBar.h"
 
 #include "App.h"
+#include "DocumentsModel.h"
 #include "SelectionModel.h"
 #include "ViewModel.h"
+#include "Window.h"
 
 #include <dtk/ui/Action.h>
 #include <dtk/ui/FileBrowser.h>
diff --git a/bin/toucan-edit/PlaybackModel.h b/bin/toucan-edit/PlaybackModel.h
index d0c4f26..5eab5d1 100644
--- a/bin/toucan-edit/PlaybackModel.h
+++ b/bin/toucan-edit/PlaybackModel.h
@@ -4,11 +4,11 @@
 
 #pragma once
 
-#include <opentimelineio/timeline.h>
-
 #include <dtk/core/ObservableValue.h>
 #include <dtk/core/Timer.h>
 
+#include <opentimelineio/version.h>
+
 namespace toucan
 {
     enum FrameAction
diff --git a/bin/toucan-edit/Stack.h b/bin/toucan-edit/Stack.h
index 9113264..dc9fb40 100644
--- a/bin/toucan-edit/Stack.h
+++ b/bin/toucan-edit/Stack.h
@@ -6,8 +6,6 @@
 
 #include "IContainer.h"
 
-#include <vector>
-
 namespace toucan
 {
     class Stack : public IContainer
diff --git a/bin/toucan-edit/StackWidget.cpp b/bin/toucan-edit/StackWidget.cpp
index 9337a7a..89b90f5 100644
--- a/bin/toucan-edit/StackWidget.cpp
+++ b/bin/toucan-edit/StackWidget.cpp
@@ -4,6 +4,8 @@
 
 #include "StackWidget.h"
 
+#include "Stack.h"
+
 #include <dtk/ui/DrawUtil.h>
 #include <dtk/core/RenderUtil.h>
 
diff --git a/bin/toucan-edit/StackWidget.h b/bin/toucan-edit/StackWidget.h
index d0a924f..8cea2af 100644
--- a/bin/toucan-edit/StackWidget.h
+++ b/bin/toucan-edit/StackWidget.h
@@ -5,10 +5,11 @@
 #pragma once
 
 #include "IItemWidget.h"
-#include "Stack.h"
 
 namespace toucan
 {
+    class Stack;
+
     class StackWidget : public IItemWidget
     {
     protected:
diff --git a/bin/toucan-edit/TimelineConvert.h b/bin/toucan-edit/TimelineConvert.h
index 3a15510..d5efb05 100644
--- a/bin/toucan-edit/TimelineConvert.h
+++ b/bin/toucan-edit/TimelineConvert.h
@@ -6,8 +6,6 @@
 
 #include "IContainer.h"
 
-#include <vector>
-
 namespace toucan
 {
     struct TrackKind
@@ -15,6 +13,7 @@ namespace toucan
         static const std::string video;
         static const std::string audio;
     };
+
     class Track : public IContainer
     {
     public:
diff --git a/bin/toucan-edit/TimelineView.h b/bin/toucan-edit/TimelineView.h
index 3ed1837..34292a8 100644
--- a/bin/toucan-edit/TimelineView.h
+++ b/bin/toucan-edit/TimelineView.h
@@ -4,11 +4,11 @@
 
 #pragma once
 
-#include "TimeUnitsModel.h"
-
 #include <dtk/ui/ScrollWidget.h>
 #include <dtk/core/ObservableList.h>
 
+#include <opentimelineio/version.h>
+
 namespace toucan
 {
     class App;
diff --git a/bin/toucan-edit/Track.h b/bin/toucan-edit/Track.h
index 3a15510..ea6479a 100644
--- a/bin/toucan-edit/Track.h
+++ b/bin/toucan-edit/Track.h
@@ -6,8 +6,6 @@
 
 #include "IContainer.h"
 
-#include <vector>
-
 namespace toucan
 {
     struct TrackKind
diff --git a/bin/toucan-edit/TrackWidget.cpp b/bin/toucan-edit/TrackWidget.cpp
index 10378c6..d7e68b5 100644
--- a/bin/toucan-edit/TrackWidget.cpp
+++ b/bin/toucan-edit/TrackWidget.cpp
@@ -4,6 +4,8 @@
 
 #include "TrackWidget.h"
 
+#include "Track.h"
+
 #include <dtk/ui/DrawUtil.h>
 #include <dtk/core/RenderUtil.h>
 
diff --git a/bin/toucan-edit/TrackWidget.h b/bin/toucan-edit/TrackWidget.h
index 5f37364..d64af05 100644
--- a/bin/toucan-edit/TrackWidget.h
+++ b/bin/toucan-edit/TrackWidget.h
@@ -5,10 +5,11 @@
 #pragma once
 
 #include "IItemWidget.h"
-#include "Track.h"
 
 namespace toucan
 {
+    class Track;
+
     class TrackWidget : public IItemWidget
     {
     protected:
diff --git a/bin/toucan-edit/Window.cpp b/bin/toucan-edit/Window.cpp
index dcc7763..4a6860c 100644
--- a/bin/toucan-edit/Window.cpp
+++ b/bin/toucan-edit/Window.cpp
@@ -6,6 +6,7 @@
 
 #include "App.h"
 #include "DocumentTab.h"
+#include "DocumentsModel.h"
 #include "MenuBar.h"
 
 #include <dtk/ui/Divider.h>
diff --git a/bin/toucan-edit/main.cpp b/bin/toucan-edit/main.cpp
index 668e026..a74e81b 100644
--- a/bin/toucan-edit/main.cpp
+++ b/bin/toucan-edit/main.cpp
@@ -4,6 +4,8 @@
 
 #include "App.h"
 
+#include <dtk/core/Context.h>
+
 DTK_MAIN()
 {
     try