The screenshot is attached and I'm not sure this is something that is the fault of Ext but I thought I'd ask.
I have an Ext window with an iframe as the content. In this case, the src of the iframe is a pdf file. I have a tbar on the window with the button you see and the button has two options... Edit and delete. Anyway, the menu shows up behind the embedded pdf file. I've monkeyed with z-indexes in firebug and it didn't do any good. I've also added wmode="transparent" in the embed tag through firebug and it didn't do any good either.