I can't change the transparency level of my K menu. I change it to 50% for example, and nothing happens. When I get back to the configuration area, it is back on 91% again.
What window decoration theme are you using? What style? Some of those themes don't support menu tranparancy as configured by kde but you can usually set it up through the theme it self. Like Baghira I don't think lets you do it unless you klick the configure button on the kcontrol style screen and the look for tranparency. Hope this helps.