With multiple monitors it is helpfull to have your marked workspace on just one monitor. My desktop is 3200x2400 (two 1600x1200 lcds) so 400 pixels doesn't help. Having the workspace margins able to adjust up to 16000 would be a (hopefully) easy and fast way of better supporting multi-monitor setups like mine. Thanks for at least the due consideration.
oliver, I think this is because in xfwm4/mcs-plugin/margins.c in add_margins_page the limit is 1/4 of the result of gdk_screen_height(), which gives only the height of 1 screen (reproducible for me on my setup as well, although I dont have 'real' xinerama, just nvidia tv out xinerama emulation ;)) Or am I on the wrong track here ? ;)
Margins aren't for emulating Xinerama: xfce has got a pretty good Xienarama support since version 3, the user should simply enable Xinerama in xfce. It's really not a bug, just a misunderstanding/misuse of margins. Olivier.
I resolve this as it's not a bug. Margins aren't for this use.