The original UFO and/or TFTD had a tiny bug in the "Graphs" screen : the top-right button that returns to geoscape was effectively larger than it looked like (it extended maybe 8 extra pixels down).
The extra space overlapped with the position of the "graphs" button in geoscape. So if you placed your mouse cursor there, you no longer had to move the mouse : you could click click click repeatedly, and keep your eyes on the graph lines to watch for any rising UFO activity.
OpenXcom doesn't have this bug, so you have to move the mouse cursor each time (and see where you click).
I can't find this piece of information anywhere (even on Ufopaedia), so I thought it was worth sharing here.