kde 4 - What to break in KDE to disable transparency?

In KDE 4.9 one can disable the transparency of most items, but not of the Plasma Panel. However, that thing annoys me to all extent. I cannot have applications full-screened then Alt-Tab to another window as the full-screen application bleeds through the panel and I can no longer make out what is actually in the panel (such as reading the clock). Is there any file that transparency depends on that I can simply rm away?

Note that turning off all effects is not a solution. I use the effects for some disability issues.

Thanks.