Looks like it is not possible to get image clicks for items inside a canvas because all mousedown/up and click events are sent to the canvas.
So I had to loop through all tiles and check which tile is clicked to modify it.
Tiles and panning can be selected from the right toolbar. Here is the link :
The plan is to modify the maps here and then save them to a mysql database, then the game will load the list of tiles from the db instead of creating a random map every time.