What is Xinerama (used for) ?

Hi there,

Xinerama is used in
desktop/Executable_oosplash.mk :
    desktop/unx/source/splashx.c
vcl/Library_vclplug_gen.mk :
    vcl/unx/generic/app/saldisp.cxx

It has quite complicated check in configure.
When cross-compiling I ended up with USE_XINERAMA=NO although it
should be available. (noticed by accident)
How should I fix it ?
Is that something we want continue to use ?
If so, do we need any checks for that in configure or we can assume
it's there like for test "$_os" = "Darwin";

Thanks,
Matus