Following Scott's link here I decided to download some themes. I have set Firefox to automatically save *.themepack files and now I want to do the same for *.deskthemepack files, but FF doesn't allow me to set it to 'Do this automatically for files like these from now on' (the option is grayed out).
I know there is a way around this, (I've added pspimage and psp files somewhere in the past too) but I forgot how to do it :S
