That's a good bug report, thank you. There is another upper limit hiding down deep in one of the support classes that caps things at 25000x25000 and fails in a bad way if it's larger than that. I removed those limits and it'll now crash nicely when it hits system hardware limits (which should be 32768 in any dimension due to use of BMP features internally). I'll try to get that rebuilt and uploaded at some point, but I don't know for sure when that might happen.