I'm using unity 5.3.7p2 personal...
when I play my project in unity editor, following errors also appears.
Too many vertices on one panel: 65244
UnityEngine.Debug:LogError(Object)
UIDrawCall:UpdateGeometry(Int32) (at Assets/NGUI/Scripts/Internal/UIDrawCall.cs:601)
UIPanel:FillDrawCall(UIDrawCall) (at Assets/NGUI/Scripts/UI/UIPanel.cs:1497)
UIPanel:UpdateSelf() (at Assets/NGUI/Scripts/UI/UIPanel.cs:1325)
UIPanel:LateUpdate() (at Assets/NGUI/Scripts/UI/UIPanel.cs:1268)
ArgumentOutOfRangeException: Argument is out of range.
Parameter name: index
System.Collections.Generic.List`1[UnityEditor.TreeViewItem].get_Item (Int32 index) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Collections.Generic/List.cs:633)
UnityEditor.GameObjectTreeViewDataSource.GetItem (Int32 row) (at C:/buildslave/unity/build/Editor/Mono/GUI/TreeView/GameObjectTreeViewDataSource.cs:131)
UnityEditor.GameObjectTreeViewGUI.DoStickySceneHeaders () (at C:/buildslave/unity/build/Editor/Mono/GUI/TreeView/GameObjectTreeViewGUI.cs:113)
UnityEditor.GameObjectTreeViewGUI.BeginRowGUI () (at C:/buildslave/unity/build/Editor/Mono/GUI/TreeView/GameObjectTreeViewGUI.cs:182)
UnityEditor.TreeView.OnGUI (Rect rect, Int32 keyboardControlID) (at C:/buildslave/unity/build/Editor/Mono/GUI/TreeView/TreeView.cs:494)
UnityEditor.SceneHierarchyWindow.DoTreeView (Single searchPathHeight) (at C:/buildslave/unity/build/Editor/Mono/SceneHierarchyWindow.cs:505)
UnityEditor.SceneHierarchyWindow.OnGUI () (at C:/buildslave/unity/build/Editor/Mono/SceneHierarchyWindow.cs:320)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
new version's UI Panel has a check box : UV2 (for custom shader effects) - I didn't see this in previous version.
if I check it, it seems show NGUI panel in Unity editor mode (when I upgraded NGUI, my NGUI ui's were vanished and it showed errors) but if I reload this scene, it's unchecked (I don't know why

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