I notice a bug on the new windowing code, which resides in release-45 or newer versions of Cygwin/X. To reproduce: 1) Invoke XWin.exe in -multiwindow mode. 2) Open 2 windows (A and B) and make them overlapped. 3) Minimize window A. 4) Minimize window B. 5) Restore window B. Then you will see that the contents of window A are drawn in window B in the overlapped area.
I suspect the bug with MSVDM reported by Andrew Braverman may be the same symptom. As a workaround, you can get back the correct Z order by restoring window A (in the above example). I will work to fix the problem as soon as possible. Takuma Murakami