#5 Middle mouse button inconsistent

[Corey Keasling]

I found inconsistent behavior with using the middle
mouse button (mmb). Clicking with mmb on mini-map
causes the main win to jump, and then jump back before
scrolling. Clicking mmb on other displays (finance or
unemployment graph) advances the display. Probably
only lmb should advance display. Also, I'm not sure if
mmb should initiate main win scrolling if the click was
made outside the main win.