something that is bugging the hell out of me (see attachment).
you can't use resoultions above 2048x1200, doing so just cuts it all off, and leaves either black, or jargon.
see link, this is r3863 with max resolution changed to 3200x1600.
http://www.tt-forums.net/viewtopic.php?t=23957
there is a hardcoded limit of 2048x1200, but i do not see any reason why this can't be incresed.
see download link
http://www.tt-forums.net/download.php?id=45146
this apeared to work fine.
my sugestion, either change the variables:
MAX_SCREEN_WIDTH = 2048
MAX_SCREEN_HEIGHT = 1200
in openttd.h to something more "Modern", or make it some kind of value read from openttd.cfg. as you can see in the screenshots in that thread, modern screen resolutions can go as high as 2560x1600 per panel(a regular VGA or DVI port can do 2048x1536, which is higher than what OTTD currently allows. i can run my screen at that resolution, just not in OTTD, which is probably the only place i would use the res because the feature makes use of a movable 1600x1200 window.), and can be used either way up, and duel screening is also very popular now. you can even buy screens with 2 to 6 panels in them.
my sugestion is make them a line somewhere in openttd.cfg, however a default of something higher, like atleast 3200x1600. this allows sideways twinscreening of 1600x1200 screens(which i have) aswell as using them in portrait mode, instead of landscape.