Of course, I removed that call. It is not the culprit though. Well, at least as far as not updating the menu bar area of the control panel window is concerned. So far I resorted to
FP.Open with State=Minimized and then again FP.Open with State=Standard.
This works most of the time but even after doing this I sometimes get a fully black menu bar. Then, when I click on the place in it where "File" is supposed to be, that item does show up normally (black on grey) and works while the rest of the menu bar remains black. Then I have to minimize and restore the CP window again for the rest of the menu bar to become displayed correctly, i.e. in grey color, not black. I think this is an obvious LabVIEW bug related to dynamic menu manipulation, not specifically the CEF's problem. The worst part is it is intermittent. Sometimes the new menu bar is displayed correctly right away.