Binary package hint: gnome-panel
On a panel, there is a one pixel wide area on the far right where an applet can't seem to go. This is a poor usability design as, according to Fitts' Law, the corner is _the_ place to be able to click if nowhere else, because it requires no effort to find it. Just slam the mouse toward it.
While there is nothing keeping people from slamming the mouse to a corner, the dead pixel area means that any clicks are wasted and they must meticulously move the cursor a mere 1 pixel to the left.
It needs to be easy to find the corner stuff, as people tend to put the more used options there, be it the shut down button or the deskbar button.
To reproduce:
1) Start up Ubuntu
2) Right click the panel > Add to Panel
3) Add, say, 'Force Quit'
4) Move the force quit button all the way to the right.
5) Send your mouse flying toward that corner and click.
Nothing happens. Aggrevating after the 3rd time, let alone daily.
I am unable to confirm this on Feisty... What release of Ubuntu are you using?