Hi /Klaus,
You asked a question,
Question: how can vm-display-X11.so be made, what's the trick?
And here is an answer: Make sure, your gcc knows about the X11 includes and your library path includes the X11 shared libs before you run configure.
Check the makefile generated by config (in directory bld) for the target:
vm-display-X11${la} : @$(SHELL) -ec 'cd vm-display-X11; $(MAKE) vm-display-X11${la}'
And then check the file bld/libtool which is a shell script generated by config which is supposed to generate the shared objects.
Hope, that helps.
Wolfgang -- Weniger, aber besser.