In triplea, when you right-click-drag the mouse on the map, it scrolls the map. This is very useful.
Also in triplea during the move phase, when you right-click-release the mouse somewhere on the map, it deselects that last unit you had selected.
So, if you have some units selected during a move phase, and then you right-click-drag the mouse, it scrolls the map (good), but then when you release the right mouse button, it then deselects a unit (bad). It should be smart enough to not deselect the last unit if the map has been scrolled during that right-click event.