[Bug]: exception raised in SpanSelector callback puts the selector in an invalid state for later interactions

Bug summary

When the callback of a SpanSelector raises an exception, the _eventpress attribute is not cleared, which leads to weird behaviors later on.

Code for reproduction

from pylab import *

top, bot = figure(layout="constrained", figsize=(6, 5)).subplots(2)
# the top selector's callback intentionally raises an exception.
sel_top = mpl.widgets.SpanSelector(top, lambda *args: 1/0, "horizontal")
sel_bot = mpl.widgets.SpanSelector(bot, print, "vertical")

show()

Actual outcome

Interact with the top spanselector (an exception is thrown when the mouse button is released -- this is normal). Then interact with the bottom one: now it appears as if you were also dragging the top selector at the same time.

Expected outcome

The top selector doesn't move when we interact with the bottom selector.

Additional information

Likely the correct fix involves wrapping the callback in a try... finally so that the cleanup that needs to be done (resetting _eventpress, etc.) occurs no matter what, but any exception still gets propagated out. I didn't really follow whether that needs to be done in release() or in _release(), though. Or maybe the release handler can start by doing all the necessary cleanup and call the callback at the very end.

Likely also worth checking whether similar issues occur with other widgets.

Operating system

macos

Matplotlib Version

3.12.0.dev569+g2153774ae

Matplotlib Backend

qtagg

Python version

3.14

Jupyter version

none

Installation

git checkout