By the way having there's no reason for the player(!) to have the map editor accessible from the main executable at all. You don't start the game and go 'Why don't I edit the map I'm about to play first.'
The opposite however is true, when you open the map editor and make/edit a map, at some point the user will want to run the game and test his map. Functionality in an editor to run the game with the map as is open in the editor is nice to have.