string.c file is based on msvcp90/string.c, there are many differences
between these files. Other files were copied from msvcp90.

user32: Add some tests for SetFocus/SetActiveWindow called on invalid or belonging to another thread windows.

This is the same value, but makes it more obvious where e.g. an "Unhandled
basetype D3D10_SVT_VOID." message would come from.