Firefox wont make a new tab while i'm on a page with flash elements.
Whenever i'm on a page with flash elements I cannot make a new tab by hitting Ctrl+T. though Ctrl+click on a link and selecting New Tab from the menue still works. if I have 2 tabs open and one with flash I can go the one without flash on the page and use Ctrl+T make a new tab.
Opaite Mbohovái (1)
If a plugin has focus then that plugin handles all key presses, so you can't open a new tab via the keyboard unless you first set focus outside that Flash object.