A brief summary of some thoughts here:

• fontsize for legend_handler is documented as "integer in pixels"

• the only place it is passed internally is inlegend.py, wherelegend_artist is called, where it is evident that the value being passed is a floating point number in points (self._fontsize, set at init time as explicitly the font size in points)

• for most handlers, font size isn't even used (even in cases where itis used, it is multiplied by values with a default of 0 which are, at least internally, never set to non-zero values)

• the exception where the fontsize comes into play and uses a non-zero value are asmarker_pad and[xy]err_pad scale factor

• even in such a case, the computation is always floating point math anyway, so even if we say it should be pixels, float type is still appropriate, though the implementation should probably be adjusted. (partial pixels are a thing, especially with HiDPI screens)

• If we are actually happy with current behavior, the docs should be updated to reflect it is float size in points rather than int size in pixels

If it isn't in points it probably should be in points 'cause consistency. Is there a way to test by passing the same # to this method and something that's documented as pixel and seeing if they look the same, or nah 'cause the numbers get multiplied in different ways before they hit the renderer?

(I think we should maybe define a custom float type "points", but that's part of the larger internal typing discussion)

If it is in points, then where we use it needs to become dpi aware?