Update to my previous message:
TrueColor is read-only, and DirectColor is
read-write. So, if the 1024 entries in
the color map of the graphics card are
the same as the video lut, I would need a
direct color visual.
Further I found out, that there are 168
visuals, and only the first group has these 11
bits. VisualID 0x23, which is listed by
xdpyinfo after 0x90, has 10 bits, but is true
color. OTOH, all DirectColor Visual have those
11 bits. So, while it is possible to select one
of the direct color visuals in xorg.conf (which
yields unreadable menus), this still would be
true color, and should therefore be read-only.
How significant is that test for dispwin
anyway? Besides 1 java program, I haven't seen
any other not working normally.