Well I think all those who want some kind of tile editor want to (in my opinion):
-to be able to "paint" with the mouse click tiles that are placed orthogonally (like some kind of by default snap to grid), these tiles having the ability to be over or below moving elements/characters/player. Or being able to draw the tiles in the different layers and they fit accordingly.
Yeah snap to grid would probably be something everybody would want, but the tiles would still be 4 sided, so iso/ ortho would already be available that way.
-the tiles to be grouped in one "single large image" or "single set of images" where you can select 1 or a few more to do something like a cluster of tiles paint (for example a tree is made of 3 tiles so you can repeat the middle tile to make taller trees, but selecting the 3 tiles at the same time lets you draw many trees doing 1 click per tree).
I guess this is the most important or basic.
Sounds nice, but would require a lot more events than its probably worth.
But Tokimsom ask for tiles that has properties/values in it; making sound per tile can be done by using an invisibles areas below the graphics if you ask me no need for precision there, but a graphical transformation per tile touched can get tricky without per tile interaction...mmmh...
Um, yeah you cant really import private variables, or create new objects.
That's just way too specialized.
Basically you want it to be as simple as possible, so that everybody can use it.
But set up so that you can do more if you want.