As I discussed with Stefan & Mihai at X2Go Gathering 2015: the aforementioned area to find what change probably caused the

1. VcXsrv 1.1.2 is not affected, so this appears to be a regression in VcXsrv.
2. It is safe to assume that it is a regression in the multiwindow code in VcXsrv (and in other X servers for Windows), xorg-server/hw/xwin/winmultiwindow*
3. We should bisect released versions/builds of VcXsrv until we find which version was 1st affected, and then compare their source code in

regression. If need be, we will build old git revisions in between those released versions. 4. I have started doing #3 and recording the results in this spreadsheet: https://docs.google.com/spreadsheets/d/1cVe7UELbJqLEFsE20v1-weUWyW-pQByTAkeU...

-Mike#2