Deleting 'selection changed' trigger handler failed

[goddard@…]

The following bug report has been submitted:
Platform:        Darwin-17.7.0-x86_64-i386-64bit
ChimeraX Version: 0.91 (2019-07-07)
Description
opened 6n2y, clicked log chain table to show sequence of chains A,B,C, clicked helix to select all helices, clicked close button on window frame of sequence viewer producing this error,

Log:
UCSF ChimeraX version: 0.91 (2019-07-07)  
© 2016-2019 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open /Users/goddard/ucsf/presentations/stanford-
jul2019/chimerax_tutorial/6n2y.cif

6n2y.cif title:  
Bacillus PS3 ATP synthase class 1 [more info...]  
  
Chain information for 6n2y.cif #1  
---  
Chain | Description  
A B C | ATP synthase subunit α  
D E F | ATP synthase subunit β  
G | ATP synthase γ chain  
H | ATP synthase ε chain  
I | ATP synthase subunit δ  
a | ATP synthase subunit a  
b1 | ATP synthase subunit b  
b2 | ATP synthase subunit b  
c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 | ATP synthase subunit c  
  
Non-standard residues in 6n2y.cif #1  
---  
ADP — adenosine-5'-diphosphate  
ATP — adenosine-5'-triphosphate  
MG — magnesium ion  
PO4 — phosphate ion  
  

> lighting simple

> select /A:2-501

3827 atoms, 3888 bonds, 1 model selected  

> sequence chain #1/A#1/B#1/C

Alignment identifier is 1  
Traceback (most recent call last):  
File "/Users/goddard/Desktop/ChimeraX July 7
2019.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/ui/gui.py", line 1590, in <lambda>  
dw.closeEvent = lambda e, tw=tool_window, mw=mw: mw.close_request(tw, e)  
File "/Users/goddard/Desktop/ChimeraX July 7
2019.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/ui/gui.py", line 543, in close_request  
tool_instance.delete()  
File "/Users/goddard/Desktop/ChimeraX July 7
2019.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/seq-view/tool.py", line 494, in delete  
self.region_browser.destroy()  
File "/Users/goddard/Desktop/ChimeraX July 7
2019.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/seq-view/region_browser.py", line 551, in destroy  
atomic.get_triggers().remove_handler(self._sel_change_handler)  
File "/Users/goddard/Desktop/ChimeraX July 7
2019.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/core/triggerset.py", line 380, in remove_handler  
self._triggers[handler._name].delete(handler)  
KeyError: 'selection changed'  
  
KeyError: 'selection changed'  
  
File "/Users/goddard/Desktop/ChimeraX July 7
2019.app/Contents/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-
packages/chimerax/core/triggerset.py", line 380, in remove_handler  
self._triggers[handler._name].delete(handler)  
  
See log for complete Python traceback.  
  




OpenGL version: 4.1 NVIDIA-10.32.0 355.11.10.10.40.102
OpenGL renderer: NVIDIA GeForce GT 650M OpenGL Engine
OpenGL vendor: NVIDIA Corporation

[pett]

region browser's destroy() didn't account for the fact that selection change was now being handled by listening to session triggers rather than atomic triggers