In case anyone cares, and would like to find out more on this topic, This distortion is called "Keystoning" In the world of Architectural photography it is a HUGE No,No. I have never used photogimps tools to correct this. (have always been lucky enough to have access to a view camera) ASalina......looks like you did a great job with your available tools. It's good to know that they are Quite useable. (can't always pack a view camera around)