This post is also available at my personal web site: http://milosophical.me/blog/2009/02/20/xming-screen-size.html
My work’s notebook (Windows XP) is running Xming as it’s X11 server, and it travels between work, home and on the train.
My work office has a docking station and a rotating second display. Typically if I start Xming with this display plugged in, Xming will adjust it’s screen size to use both displays, but if I start it without the screen plugged in, it’ll size to just the notebook screen. If I later add the 2nd screen (by docking the notebook), Xming won’t use it without a restart. Also if I rotate the screen, only the top 1200 pixels will be used by Xming.
The solution is to specify a screen size to begin with that is as wide and tall as both of the screens. On my docked notebook the two displays are the notebook’s display (1920×1200 pixels) and 2nd display (1600×1200 pixels, which rotates to 1200×1600). So that means the combined screen width is 3520 pixels, and the tallest screen hight is 1600 pixels. Specify this to Xming when it starts:
path\to\xming.exe :0 -clipboard -multiwindow -screen 0 3520x1600
Now I can add/remove/rotate the second screen and still use all of it without restarting Xming.