scribbling tool (eg for labeling markers)

[Emmanuelle Gouillart]

	Hello,

	during the Euroscipy sprints, Stéfan and Josh mentioned that they
frequently use homebrewed scripts in order to scribble on an image and
retrieve the coordinates of scribbled pixels, e.g. in order to determine
some markers for image segmentation. Stéfan or Josh, would you mind
sharing snippets of code showing how this can be done?

	Thanks!
	Emmanuelle