Pass wxWindow instead of HWND to it as in most cases we already have wxWindow for the HWND we have and calling wxFindWinFromHandle() once more is unnecessary. This also makes the code of MSWGetBgBrushForChild() slightly simpler. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62932 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775