If you’re using a NVidia card with TwinView and the Xinerama extension replacement, you may find some applications are suddenly not behaving as they used to. Some applications do not like the way NVidia has properly implemented a multiple display framebuffer, and break horribly.

Some examples. Firefox and Thunderbird load up with font sizes that are huge. Kaffeine, using the Xine engine, plays videos that are very stretched or compressed, and GnuCash will incorrectly render your transaction reports such that the graphics are completely unreadable.

The solution for Mozilla and its kin is fortunately rather simple. You can change the value of the the Display resolution: option from System setting to either 96 dpi or 72 dpi or select your own favorite. That mostly resolves the issue.

I haven’t found a workaround for Kaffine and Xine yet, except to use mplayer instead. I never play videos on my system with TwinView anyway, so it hasn’t been an issue.

For GnuCash’s reports, the only workable solution I have found is to run a VNC server instance and then run GnuCash from within it to generate my reports for viewing. On Debian GNU/Linux, I simply installed vnc4server. When run as my user, it will create a new X server running on port 5901 with the options specified in $HOME/.vnc/xstartup:

#!/bin/sh
 
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
konsole &
xfwm4 &

You’ll need to create /$HOME/.vnc/passwd or things won’t work. Pick a password you like.

$ vncpasswd ~/.vnc/passwd

Then, simply point a VNC viewer at localhost:5901.

There are doubtless countless other applications that work fine under X’s Xinerama implementation, but fail under NVidia’s TwinView. Fortunately I haven’t encountered any other applications that I use that suffer such a fate.