When you resume from sleep, the Firefox window is visible but it's a background window, not the active window, and the menu bar is displayed in that window? Then when you make the window active, the menu bar is hidden as expected?

There are two keys that can cause Firefox to display the menu bar in the active window: Alt and F10

If you click anywhere other than the menu bar at that point, it will hide again.

But I don't know how the menu could get enabled in a background window. ???

Thanks for the reply,

Ah a good point about background foreground - I tried it out. If I make another window the foreground one and after resuming from sleep the firefox window does not show the menu bar as expected. If I make firefox the active window and after resuming from sleep it shows the menu bar until I click anywhere on the firefox window and the menu bar goes away.

I also tested by not hitting the "sleep" button the keyboard (Function + F12) but setting windows to sleep after 1 minute of inactivity and I still saw the menu bar appear - I was thinking it may of been the button I pressing for sleep was causing the menu bar to show before the sleep happened.

It could also be a windows thing and not firefox.