Setting minimum font size on Firefox, makes the layout break

After setting the "Minimum Font Size" parameter on Firefox 3.6, makes the layout break on the Source View inside FishEye.

Steps to reproduce:

• Access a source view in any FishEye repository
• Access "Preferences on Firefox;
• Select the "Content" tab
• Click on the Advanced Button on the right side of the "Default Font + Size" preferences;
• The option "Minimum Font Size" that is set to NONE, must be set to 14;

The error reproduces on the versions 3.6 and 4.0 of Firefox.
The first Screenshot is from a Default font config on browser. The second is after setting the parameter.

Related Issues:
https://support.atlassian.com/browse/JST-20619

Cheers
Nícolas