Thanks for the fix @outofculture that's too bad the in operator doesn't work, it feels so right for this use case.

Elsewhere in ROI.py we use ev.button() & self.acceptedMouseButtons() the int version I'm pretty sure was broken on PyQt6 6.0.0, but we don't support that version due to their non-integer alternative to enums.

Should we change the other usage of self.acceptedMouseButtons() or should we do away with the integer casting (or just use two different methods)?

Oh, I hadn't seen it used elsewhere. int casting isn't necessary, so I'm fine skipping that. Well, fine except that now my branch name isn't clever, but 🤷🏽

Well, fine except that now my branch name isn't clever, but 🤷🏽

we can't get everything we want in life....

       elif ev.button() & self.acceptedMouseButtons() > 0:

0fa4557 is the commit that added PyQt6 compatibility wrt to enums and flags.
No testing against > 0
I recall that you can't generally test against an integer value, It might end up being False just because you are comparing two different types.
It would be a good idea to physically test out the change with a PyQt6 venv.

Ran the ImageView example in PyQt6 6.0.3 and 6.1 and did a mouse click within the ROI

[19:54:39]  Error sending click event:

    |==============================>>
    |  Traceback (most recent call last):
    |    File "C:\work\github\pyqtgraph\examples\ImageView.py", line 67, in <module>
    |      pg.exec()
    |    File "C:\work\github\pyqtgraph\pyqtgraph\Qt.py", line 447, in exec_
    |      return app.exec() if hasattr(app, 'exec') else app.exec_()
    |    File "C:\work\github\pyqtgraph\pyqtgraph\widgets\GraphicsView.py", line 355, in mouseReleaseEvent
    |      super().mouseReleaseEvent(ev)
    |    File "C:\work\github\pyqtgraph\pyqtgraph\GraphicsScene\GraphicsScene.py", line 240, in mouseReleaseEvent
    |      if self.sendClickEvent(cev[0]):
    |    File "C:\work\github\pyqtgraph\pyqtgraph\GraphicsScene\GraphicsScene.py", line 389, in sendClickEvent
    |      debug.printExc("Error sending click event:")
    |    --- exception caught here ---
    |    File "C:\work\github\pyqtgraph\pyqtgraph\GraphicsScene\GraphicsScene.py", line 387, in sendClickEvent
    |      item.mouseClickEvent(ev)
    |    File "C:\work\github\pyqtgraph\pyqtgraph\graphicsItems\ROI.py", line 804, in mouseClickEvent
    |      elif ev.button() & self.acceptedMouseButtons() > 0:
    |  TypeError: '>' not supported between instances of 'MouseButtons' and 'int'
    |==============================<<

@pijyoi I'm going to fix this in #1807 thanks for catching it.

I swear, qt bindings are never happy (PyQt5 5.12 + Python 3.8)

================================================================================= warnings summary ==================================================================================
tests/graphicsItems/test_ROI.py::test_PolyLineROI
  /Users/ogi/Developer/pyqtgraph/pyqtgraph/graphicsItems/ROI.py:804: DeprecationWarning: an integer is required (got type MouseButtons).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
    elif ev.button() & self.acceptedMouseButtons():

-- Docs: https://docs.pytest.org/en/stable/warnings.html

I think I may just suppress this warning.

While the fix was easy, why didn't the new test that was added catch this is the mystery, looking into that now.

oh, it did catch it, but it was suppressed; ... that's a problem; you can see the exception when you run pytest -s

EDIT: and here is why an exception wasn't raised...