About the window size... I haven't thought about that...sorry. It's my first real programming project and I've been actually just learning how to do things in java and I don't know how to design a proper resizable window...
It's not possible to draw in the program (maybe in the future). At the moment you can only load an image, (eventually resize it... I've cut the dither and palette options for the release as they were too buggy) and convert it to a software sprite or screen data (or just generate an LPT for given screen parameters). I added maxam->pasmo syntax translation but it's not fully implemented, so may need some corrections. Also for ep you will have to change all "next line" code... (sorry, the first release was rushed, so it's not fully functional).