Cool. I use GameMaker: Studio and have been working on my own level editor recently.
Saving is a little weird. I use ini files for saving and loading levels.
I liked your game, by the way :
Thank you! :) Ini saving is a problem for me. Save is working as it should but I don't know where the save is. Game Maker 8 make save directly into the folder. That is the main reason why I'm using GM8 for this game.