https://bugs.winehq.org/show_bug.cgi?id=37706
--- Comment #2 from Bruno Jesus 00cpxxx@gmail.com --- I'm in a Windows 8.1 machine right now, so just to increase tests:
ScrollWindowEx() before ShowWindow(nCmdShow): NULLREGION ScrollWindowEx() after ShowWindow(nCmdShow) and ShowWindow(SW_HIDE): NULLREGION ScrollWindowEx() after only ShowWindow(nCmdShow): SIMPLEREGION