Fortunately, you can get around it:
1. Type about:config into the Firefox location bar.
2. Right-click on the page and select New and then Integer.
3. Name it privacy.popups.disable_from_plugins
4. Set the value to 2.
The possible values are:
0: Allow all popups from plugins
1: Allow popups, but limit them to dom.popup_maximum
2: Block popups from plugins
3: Block popups from plugins, even on whitelisted sites
Hope this helps!