Comment 2 for bug 375905

I can reproduce this behavior on my Logitech MX1000 in Fedora 11 by holding down the scroll wheel button ("clicking" the scroll wheel but not releasing the click).

1. Hover cursor over e.g. an empty portion of a GNOME panel, or a launcher icon on the panel.
2. Click and hold down scroll wheel button and move cursor away from the panel, as if dragging it with the scroll wheel.
3. Right click mouse button (still holding down the scroll wheel button)

What results from the above steps is the context menu that you'd get from right clicking on whatever icon you "dragged" away from.