Hi Alex,
I spoke with Jon Turney (jturney), the Cygwin XWin maintainer on
#cygwin on Freenode. I also tested some options.
It sounds like the best approach to making a "full screen" secondary
monitor work is to launch VcXsrv (or Cygwin XWin) with these
arguments:
-nodecoration -screen 0 @2
For tertiary monitor, use @3 instead.
This launches Cygwin XWin in root window mode (the default) rather
than -multiwindow mode. -nodecoration hides the window decoration from
the Windows OS.
Can you please test this out and see if it meets your needs? If so, it
should be a simple change to x2goclient to launch VcXsrv this way.
Also, FYI:
It is true that if you launch Cygwin XWin or VcXsrv in fullscreen
mode, then it will always use the primary display, even when you tell
it to use the secondary:
-fullscreen -screen 0 @2
However, by telling either X server to use its older rendering engine,
you can solve this problem:
-fullscreen -engine 1 -screen 0 @2
I do not recommend this approach for x2goclient though because if you
click out of the X server, then the X server minimizes.
Note: these are the engines:
-engine engine_type_id
Override the server's automatically selected engine type:
1 - Shadow GDI
2 - Shadow DirectDraw - obsolete
4 - Shadow DirectDraw4 Non-Locking
Engine 4 is the default. Engine 2 is not available on VcXsrv. Jon
acknowledges that there is a secondary monitor limitation/bug with
Engine 4.
-Mike#2