To fix widget problem in Firefox, Mozilla
It’s no Firefox bug but a KDE one. The fix that worked for me is to install the package “gtk2-engines-qtcurve”,
then open kcontrol and go to Appearance -> GTK Styles and change the GTK Styles to “QtCurve”.
http://blog.larsneumann.net/2008/09/firefox-3-annoying-shade-on-checkboxes-and-radio-buttons/
