winforms Hiding a ToolStripMenuItem on DropDownClosed throws exception if closed by hovering over different menu item

Hiding a ToolStripMenuItem on DropDownClosed throws exception if closed by hovering over different menu item

Open jonaskohl opened this issue 3 years ago • 1 comments

.NET version

Version: 6.0.300 Commit: 8473146e7d

Also did not work in .NET Framework 4.8

Did it work in .NET Framework?

Did it work in any of the earlier releases of .NET Core or .NET 5+?

No, it did not work in any of the earlier releases of .NET Core or .NET 5+.

Issue description

Exception stack trace

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')
   at System.Collections.ArrayList.get_Item(Int32 index)
   at System.Windows.Forms.ToolStripItemCollection.get_Item(Int32 index)
   at System.Windows.Forms.ToolStrip.ClearAllSelectionsExcept(ToolStripItem item)
   at System.Windows.Forms.ToolStrip.NotifySelectionChange(ToolStripItem item)
   at System.Windows.Forms.ToolStripItem.Select()
   at System.Windows.Forms.ToolStripItem.HandleMouseEnter(EventArgs e)
   at System.Windows.Forms.ToolStrip.OnMouseMove(MouseEventArgs mea)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.ToolStrip.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, WM msg, IntPtr wparam, IntPtr lparam)

Screen recording of the issue

https://user-images.githubusercontent.com/23175424/193817496-069210c5-edd2-4014-903f-e68a3e9e67d1.mp4

Test VS solution to reproduce (includes .NET 6 and .NET Framework 4.8 projects)

Problem is probably caused by a race condition in ToolStrip.ClearAllSelectionsExcept(ToolStripItem).

Steps to reproduce

Have a MenuStrip with at least one visible and one hidden ToolStripMenuItem. Have an event listener for DropDownClosed on the hidden item which sets that item's Visible property to false.
Programatically trigger the hidden menu item by first setting menuItem.Visible = true and then calling menuItem.ShowDropDown().
Hover over another menu item, thus closing the (intially) hidden item's dropdown.
A System.ArgumentOutOfRangeException will be thrown.

Oct 04 '22 12:10 jonaskohl

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