Outline Tool

It might be too much to ask for, but I would love an option to create a pixel outline in the selected tile(s) that delineates the drawing, something like this: 

There's an option like that in the GameMaker editor, pretty useful and saves a lot of hassle. I can do something similar in realtime using drop shadows on photoshop
anyway! Pyxel Edit rules!

Comments
There should also be an option to select the thickness of the out line - how many pixels and also are those pixels connected on the edges or not.
(eg if the out line is:
XXOO OOX
XXXOOXX
XXXX
or:
XOOOOOX
XXOOOX
XX
What i'm doing:
* Use magic wand to select select transparency
* selection->inverse selection
* make duplicate of character layer
* use fill or brush tool with large brush to fill selection with black
* copy bottom layer (the black outline) to your clipboard
* paste your selection onto canvas and use offset tool or transformation tool to position.