Problem

I would like to be able to modify the alpha of both the line and marker in a legend as an extension of this example: https://matplotlib.org/stable/gallery/event_handling/legend_picking.html

However, currently the only way to access the marker in in the legend in order to set it's alpha value is via the private legline._legmarker attribute.

This is not ideal for the reasons that @jklymak noted in #9155 (comment)

This is pretty hacky, and the undrscore means it could go away.

So with the current public api the best you can achieve is:

when what I want is:

Proposed Solution

The simplest solution would be to drop the underscore on the legmarker and add modifying the marker to the example as a way of documenting.