0.6.6: Fixed issues with both canvas and scene picker

* Scene: Fixed issue, where scene picker wouldn't update correctly, when in play mode and changing active scene
* Canvas: Fixed issue, where it wasn't possible to select canvas in prefab stage

Editor/Toolbar/Tools/ToolUICanvasPickerEditorStateChanged.cs

@@ -0,0 +1,47 @@
+using Game.NavigationTool.Editor.Tools;
+using UnityEditor;
+using UnityEditor.Experimental.SceneManagement;
+using UnityEditor.SceneManagement;
+using UnityEngine.SceneManagement;
+
+namespace Game.NavigationTool.Editor.Toolbar
+{
+    [InitializeOnLoad]
+    internal static class ToolUICanvasPickerPostProcess
+    {
+        static ToolUICanvasPickerPostProcess()
+        {
+            EditorSceneManager.sceneSaved += OnSceneSaved;
+            EditorSceneManager.sceneOpened += OnSceneOpened;
+            EditorSceneManager.sceneClosed += OnSceneClosed;
+
+            PrefabStage.prefabStageOpened += OnPrefabStageOpened;
+            PrefabStage.prefabStageClosing += OnPrefabStageClosing;
+        }
+
+        private static void OnSceneSaved(Scene scene)
+        {
+            ToolUICanvasPicker.SetAsDirty();
+        }
+
+        private static void OnSceneOpened(Scene scene, OpenSceneMode mode)
+        {
+            ToolUICanvasPicker.SetAsDirty();
+        }
+
+        private static void OnSceneClosed(Scene scene)
+        {
+            ToolUICanvasPicker.SetAsDirty();
+        }
+
+        private static void OnPrefabStageOpened(PrefabStage stage)
+        {
+            ToolUICanvasPicker.SetAsDirty();
+        }
+
+        private static void OnPrefabStageClosing(PrefabStage stage)
+        {
+            ToolUICanvasPicker.SetAsDirty();
+        }
+    }
+}