draw_rubberband draws the box using the native calls in whatever GUI framework is being used. This can be a lot faster over a remote X11 connection, for example -- this is also important for the NbAgg backend where there might be a high-latency connection between the browser and the server. The RectangleSelector, as all matplotlib "widgets", uses Agg to do the drawing, so requires an expensive/high bandwidth transfer of the screen buffer.

Ok, that makes sense.
What would be the problem in using draw_rubberband inside the RectangleSelector (if available)?
I am just trying to unify things.

That may work -- definitely worth experimentation.

@fariza Closing this as the question got answered. I assume this will be replaced by a PR anyway if it works.

Please ping to have re-opened if you disagree.

This could be used to replace the line version of the RectangleSelector, but it would be nice to keep the option to draw a patch with tunable options. I will add this to my PR.

Actually, what I ended up doing is using drawRectangle while dragging, and then drawing the desired shape upon release.