Comment 11 for bug 219460

I solved the problem in my case. There was a *Mail* widget class reference in one of the gtk rc script files that I found to change my gnome panel to a dark colour. This must make the gtk engine change more widget classes than are intended. I simply commented out the line that starts with:

widget_class "*Mail*" style

e.g. in my case, it was a file named "panel_black-plastic.rc" that had a line which read:

widget_class "*Mail*" style "panel-black"

I just commented that line out, by putting a # in front of it, now that line looks like the following:

#widget_class "*Mail*" style "panel-black"

This solved both the attachments area issues and the Mail Preferences tab issues.

Hope this helps anyone else with a similar theme problem.