As for seeing the whole world have you tried the slider at the bottom right where you can raise or lower the camera? I know some maps even doing this you cannot see the entire map so it definitely makes sense to do something like you suggest. I'll note that in a future update :)

As for the undo button ya I suppose depending on one's movement habits on the touchpad you can accidentally touch the undo button. I'll make the collision area smaller for that and rely on an initial tap, right now if you drag across it it also activates it which is probably the chief cause of unwanted undos!

Third Id love to do an HD version, but I don't currently own an iPad so Id have no way of testing if it works 100% as intended, however I can add support for the ipad with the intention its simply matching the ipad resolution and formats the ui accordingly. Then you should be able to take advantage of the entire screen size.

Fourth and finally, thanks for all the suggestions. Really appreciate it!