Technorama

Set DPI for the display (default is 96dpi)

Screen size is 1366x768 pixels, (11.5 x 6.5 inches). 1366/11.5=118. 768/6.5=118

System->Preferences->Appearance.
Click on Fonts tab.
Click Details
Enter Resolution "118" dots per inch.

This fixes the Gnome desktop, and all application File and Window text sizes (just need to restart applications, or log out and back in)

Firefox uses the value returned by Xorg (check with xdpyinfo). I've not found any of the ways successful to change this. Mozilla DPI page didn't help. Felix Miata has a very useful site, check his browser dpi link (this now reports DPI as 118).

However Firefox still has small fonts. Therefore set dpi in Firefox:
about:config
layout.css.dpi (defaults to -1), change to 118.

It is possbile to start X in the correct DPI, which xdpyinfo will then report:

startx -- -dpi 118

Unfortunately this means removing the gdm login, as that does not allow specification of the DPI!

Better Firefox workaround is to install the NoSquint add-on and set it to zoom text, but not images. My DPI is 1118, divide that by 96 and I get the zoom level I need (122%)

Labels: DPI, GNU+Linux, Ubuntu