Toggle tab mode button when no non-Zotero tabs are open

[ajlyon]

The "Toggle tab mode" button is non-functional when Zotero is in an app tab and no non-Zotero tabs are open. This makes sense, since the Zotero pane needs be overlaid on a real tab, but the button shouldn't just be non-functional. It should either be disabled (with a tool-tip that explains why, in several words), or it should open a new tab and overlay the Zotero panel over that tab.

I also see a little button-like thing next to the toggle button-- see the attached screenshot.

This is all in Firefox 4.0b12pre, with the most recent multilingual build of Zotero (which is pretty much identical to Zotero 2.1 trunk in its UI, so I think this isn't an ML issue). Still cc'ing Frank in case it is ML at fault for either issue.

[simon]

In [9273]:

closes #1797, Toggle tab mode button when no non-Zotero tabs are open

clicking the toggle tab button when the Zotero tab is the only tab open will now open the home page