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KeyNotFoundException occurs when moving mouse cursor over main RibbonForm after closing the child RibbonForm. This occurs when quickly moving the cursor over the main RibbonForm.

Replication Steps:

1. Run the sample.
2. Click the "Start" button to load a second ribbon.
3. Now close the second window over the "Close" button in the ribbon.
4. Now quickly move the mouse to the ribbon of the main window in the direction of the Close (X) Button from the main ribbon.

Stack Trace:

   at System.ThrowHelper.ThrowKeyNotFoundException()

   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)

   at Syncfusion.Windows.Forms.Tools.RibbonPanel.OnMouseMove(MouseEventArgs e) in D:\Volume 1, 2020\Support sources\Tools.Windows\tools-windows\Windows\Tools.Windows\Src\Controls\RibbonPanel\RibbonPanel.cs:line 1044

   at System.Windows.Forms.Control.WmMouseMove(Message& m)

   at System.Windows.Forms.Control.WndProc(Message& m)

   at Syncfusion.Windows.Forms.Tools.RibbonPanel.WndProc(Message& m) in D:\Volume 1, 2020\Support sources\Tools.Windows\tools-windows\Windows\Tools.Windows\Src\Controls\RibbonPanel\RibbonPanel.cs:line 994

   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)

   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)

   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)

   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)

   at RibbonCloseProblem.Program.Main() in D:\Volume 1, 2020\Support\Feb 5\RibbonCloseProblem_60afe69f\RibbonCloseProblem\RibbonCloseProblem\Program.cs:line 18