A problem found its way into the latest upgrade of Firefox where the Window title bar goes missing. This seems to only occur with those people using Compiz. A simple short term fix is pressing F11 but it does not always "stick". Here is a solution that will ensure this is not a problem each time you open Firefox.
You can fix this by going into your Compiz Settings Manager (this is found in Control Center or on the optional compiz icon - downloadable from Synaptic).
Once in the Settings Manager, click on the "Workarounds" icon in the "Utility" section of the menu. Having clicked on the Workarounds icon you will get a list of options you can choose to select or unselect by putting a check in the box. Choose "Legacy full screen support" (at the top of the list) and uncheck the box. This will fix it for you.
This is a firefox regression that has crept back into the latest version.
I hope this is useful to others.