Assigning a window to HwndSource.Rootvisual throws an System.ExecutionEngineException

Hello,

we try to host a Window (in fact a class derived from Window) in a HwndSource.

When we assign the window object to the RootVisual member we get the System.ExecutionEngineException exception.

The code looks like this

HwndSourceParametershwsp =newHwndSourceParameters("blabla");

HwndSource = newHwndSource(hwsp);

Control = newMainControl(); // derived from Window