Quote: "users just click on preferences"
Quote: "Or while clicking on 'new' it asks the size."
That's not possible, since the source for the editor window itself is closed source and won't be released (because it checks whether the serial code is valid, disables the "Build Game" option on the free version, etc.) unless FPS Creator turns into a freeware application someday, which probably won't happen, or Lee itself implements this.
I personally don't think the map size should be extended yet, since the engine isn't even stable enough to handle the current size that good, major performance and speed optimizations should be made to FPS Creator, as well as DarkBasic Pro, before this is considered.
-Doomster