I'm having a hard time using my mouse to draw the precise walkable areas I want on any given game screen. I've been considering getting a Wacom writing tablet with stylus for other reasons, and just wondered if it was possible to use that with AGS to define the walkable areas, too -- i.e. instead of being limited to using the mouse.
You know that you can import the walkable areas from a file (http://www.adventuregamestudio.co.uk/manual/Importing%20a%20file%20as%20the%20walkable%20area%20mask.htm), right? Drawing them in an art package with zoom should make it a easier than doing it in AGS, and you certainly should be able to use a tablet there. It needs to be in 320x2*0 resolution (i.e. half size if your game is 640x4*0 or 800x600), but that's pretty much the same as in the editor anyway.
A random application has no way of knowing whether the cursor is moved by a stylus or a mouse. Only additional features like pressure detection or angle have to be supported by the app.