How is this possible: OnPaint processed while in WaitOne

Question

I have a ManualResetEvent. At one point, I wait on that event using WaitOne. To my amazement, I received an OnPaint event while in the

Answer 1

I have seen this behavior too for the lock() statement. Apparently the .net framework Thread classes starts a message loop when waiting for a lock on the UI thread. This just explains what is happening. The reasoning could be to prevent deadlocks when working with legacy STA COM objects. I am not aware of a way to prevent this.