Hi Mike#1,
I will try your suggestions.
Also, everyone,
I just released X2Go Client for Windows 4.0.4.0-2015.06.24 instead of 4.0.4.0-2015.06.22 (because I did the build 1.5 days later.) The alternate build with the test fix (reverting the winmultiwindow.patch) is available: http://code.x2go.org/releases/binary-win32/x2goclient/releases/4.0.4.0-2015....
-Mike#2