General layout Idea.
Have 2 tabs for the part with the actual map contents.
Models - Buildings, Fountains etc
Terrain - Water, Grass, Plants, Rocks etc
Also, have a built-in Event Editor so you can change the text from the program.
An In-depth Event Editor and Event Maker would also be good.
Then have the Event, Permissions and Header tab too.
If you can't do any of that, that's fine. I can help direct the layout, but I'm useless when it comes to writing a program.