Cool. I plan to look at the source code later. One issue I noticed: when playing with the mouse, if I click on a tile, then click on some other tile, the FIRST

Cool. I plan to look at the source code later. One issue I noticed: when playing with the mouse, if I click on a tile, then click on some other tile, the FIRST tile clicked is the one that moves - which seems like a bug and is certainly a counterintuitive input behavior.