Problem

HiDPI stuff never worked in my app because I am using Matplotlib in an embedded style in a larger tkinter picture, directly using Figure and FigureCanvas objects rather than e.g. the pyplot interface. So I don't use a figure manager at all in that thing, but the HiDPI logic is wrapped up in there.

It does make sense for pyplot to control the DPI state from a FigureManager, but I think having everything in there limits the broader usability.

Proposed solution

The initialization code in FigureManagerTk might be better exposed as a method (or methods) on FigureCanvasTk, or something backend-specific that is a user-facing API.

I just thought of this and so I'm still a little uncertain how best to expose this stuff, especially considering that parts of it need to be activated before the process ever draws a window. Happy to have a discussion with anyone to iron out the details.