[Matplotlib-users] How to draw a region of interest

Hi:

Just stared playing with matplotlib, I want to draw a polygon on top of 
an image to select a region of interest in the image.
Does anybody have any example or advice on how to interactively draw a 
polygon with the mouse by placing it's vertices's one click at a time ?
Another case that I have would be just to fill a region with a thick 
line, searched for a "doodle example" or a "paint example" but could not 
find them, any advice would be appreciated too.

      

                                                                      
Daniel.