I was using the code from #25428 (comment) to test this.

import matplotlib.pyplot as plt
plt.plot(range(5), label='bob')
leg = plt.legend()
leg.set_draggable(True, update='bbox')
plt.show()

Maybe this should get a .. versionmodified:: annotation in set_draggable?

@greglucas , I had a look at the macosx issue, and this is what's going on:

• NavigationToolbar2._update_cursor() sets NavigationToolbar2._last_cursor only when the mouse moves and the current tool requires a different cursor than the current value of _last_cursor.
• NavigationToolbar2._wait_cursor_for_draw_cm() resets the cursor to _last_cursor after drawing is finished, thus undoing any changes made through FigureCanvas.set_cursor().
• Example scripts (1, 2) solve this by calling set_cursor() every time the mouse is moved. However, this doesn't work for the specific case of Cursors.MOVE on the macosx backend: the backend changes the open hand cursor to a closed hand when the mouse is pressed. Calling set_cursor() every mouse move resets it to an open hand, but not doing that resets it to _last_cursor instead.

I think the solution might be for the macosx backend's FigureCanvas_set_cursor() to map Cursors.MOVE to the closed hand cursor if the mouse is currently pressed. Unless anyone can think of a time when this would be undesired?

On a related note, @QuLogic, should _last_cursor and _wait_cursor_for_draw_cm() be moved from NavigationToolbar2 to FigureCanvas in line with #20620? Then set_cursor() could update _last_cursor not just for the toolbar, and only actually change the cursor when necessary, but I'm not sure if widgets updating the cursor constantly even has significant overhead on any backends. Though that would have the issue that if any use case for some reason changes the cursor while a toolbar tool is active, it would need to change the cursor back to the tool's cursor afterwards.

@daniilS lets keep the macosx issues discussed in the linked PR for that. I think this is a useful addition still and just needs a rebase at this point.

I think you might need to rebase, as there seems to be some extra commits here. We have some instructions for that here: https://matplotlib.org/devdocs/devel/development_workflow.html#rewriting-commit-history

Fixed the rebase. However, I found that this PR reveals a different issue with DraggableBase: when a figure or axes is removed, disconnect() never gets called, leaving the callbacks in place, so the mouse cursor keeps changing when hovering over the place where the legend used to be. An example (video shown below):

import matplotlib.pyplot as plt

line = plt.plot(range(3), label="line")[0]
leg = plt.legend(draggable=True, loc="upper center", fontsize="xx-large", mode="expand")

plt.show(block=False)
plt.pause(1)
plt.clf()
plt.show()
# cursor still changes when hovering over the top of the figure

I think a hook should be added somewhere to call disconnect() when the associated artist is removed, but I'm not sure where would be a good place.

Perhaps _Axes._remove_legend? (via _legend._remove_method)

@anntzer thanks, that pointed me towards what I think is the right place! It looks to me like the best solution is to deparent the legend together with other artists in _AxesBase.__clear() following #24627. @tacaswell, can I just check that I'm not overlooking anything in case the legend deliberately wasn't included in that commit?