application freezing after button.focus() / no information from the debugger

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C#

VS2012

Hi,

i have come across a specific situation where my c# programm just freezes and there is no information from the debugger. In the MWE (focusbug.rar) i use a button inside a custom control (button on panel) to focus a normal button. Instead, the program just freezes.
You can trigger the error by checking the checkbox and click on the "Click Here" button.

What causes this behaviour and how can i fix it?