Thanks for playing. Yeah, the "rules" governing the mechanics in this are a bit abstract and confusing and I wasn't really able to communicate them in a way I'm really satisfied with.
As for the puzzle you got stuck on, if you're wondering: there are a few tricks you have to pick up on. First, when something is in one of those "window" looking tiles you can push them onto a grow/shrink/etc tile and the window takes on that effect. Using this you can "grow" the shrink tile to your size. After that you have to figure out how to trigger the switch that removes the window; something the same size as the switch needs to be moved onto it. The trick here is that the window tile will pick up the switch itself if you just push it onto it, but if the window has something else in it already then it will activate the switch like a box would. So you can put the (otherwise unused) split tile in the window and then push it onto the switch, which then allows you to use the enlarged shrink tile and get to the goal.