StaticColor causes problems with nx-libs

[mikedep333]

This bug corresponds to X2Go Bug 891.

By default, VcXsrv (both upstream and the X2Go/Arctica builds) offers 4 Visual Types with StaticColor:
0x211
0x212
0x213
0x214

Cygwin XWin and most Linux Xorg servers do not offer any Visual Types with StaticColor anymore (based on my limited research.)

This is a problem when VcXsrv is used with X2Go, or other nx-libs based solutions, because it causes nxagent to offer 1 Visual Type with StaticColor:
0xa6
When you suspend an nxagent session (x2go session), and try to resume it with a client (X server + nxproxy) that doe not support StaticColor, it fails to resume.

The default mode of VcXsrv is -wgl, which is affected. -swrastwgl is also affected. -nowgl is unaffected. So a workaround for many people is to launch VcXsrv with -nowgl.

VcXsrv is also unaffected when OpenGL acceleration is unavailable, such as over RDC or on a hypervisor with 3D support disabled. Presumably that causes VcXsrv to fallback to -nowgl mode.

[mikedep333]

As seen on the https://github.com/ArcticaProject/vcxsrv/tree/bugfix/bug4 branch, I have ported a patch from Cygwin XWin. I will discuss the implications for X2Go Client on the X2Go Bug report (891). The patch disables any Visual Types where 3D acceleration would not work, which empirically prevents StaticColor from being offered. I tested it with X2Go successfully.

[mikedep333]

Resolved back in 1.17.0.0-3 with commit 99bcd3b as disccused above.