Hi Daedelus,
Thanks for the swift reply.
On point 1. I know what you mean about PCB- Gcode. The first board I did with it resulted in the drill burying itself in the board without the motor running. Actually, the problem is not that you put the S command in the output file but rather it goes in after the real one. If you put it at the top of the Gcode all should be well.

3) I agree that the parameter boxes should stay. One simple solution might be to default the X, Y, X Length and Y Length boxes to 0. If they are zero when the user clicks "Create Leveled Gcode" then use the automatically generated extremities but if none zero, use those values.

Good luck with the parser.