How can I set the default text and icon sizes in some applications? I have a dell laptop with a high res screen (1920 x 1200) and I can set the default font sizes for most things using System - Settings - Appearances. However some apps do not follow these settings (e.g. Skype, Zimbra) and are much too small on my screen. Is there a way to set the default size of everything for a single app (e.g. by adding a subcommand to the launcher)?
A subsidary question is how can I set the default text size in Firefox to be something than the standard setting. This is less of a bother because I can easily use Ctrl + to increase the text size - but it would be convenient if it could start up at a size that I prefer.
With grateful thanks for any help!