The problem seems to be the velocity of the mouse hitting the edge of the screen. A lot of the times, when I move the mouse to the edge of the screen relatively slowly (not that slowly at all in my opinion) the panel shadow will show, then disappear without actually displaying the panel itself! If you continue to press the mouse against the edge, the shadow may flicker on and off, and sometimes the panel will even show eventually. This doesn't happen if you 'hit' the mouse cursor against the edge of the screen more rapidly. Very annoying!
The problem seems to be the velocity of the mouse hitting the edge of the screen. A lot of the times, when I move the mouse to the edge of the screen relatively slowly (not that slowly at all in my opinion) the panel shadow will show, then disappear without actually displaying the panel itself! If you continue to press the mouse against the edge, the shadow may flicker on and off, and sometimes the panel will even show eventually. This doesn't happen if you 'hit' the mouse cursor against the edge of the screen more rapidly. Very annoying!