QColorDialog can cause segmentation fault

[astrofrog]

Under some circumstances, glue can segfault when a QColorDialog is accessed. I've only ever seen this on @catherinezucker's computer in one environment and haven't been able to reproduce it. But just keeping a record of the error in case it can be debugged in future:

Current thread 0x00000001146c95c0 (most recent call first):
  File "/anaconda3/lib/python3.6/site-packages/glue/utils/qt/colors.py", line 166 in query_color
  File "/anaconda3/lib/python3.6/site-packages/glue/utils/misc.py", line 59 in result
  File "/anaconda3/lib/python3.6/site-packages/glue/utils/qt/colors.py", line 162 in mousePressEvent
  File "/anaconda3/lib/python3.6/site-packages/glue/app/qt/application.py", line 1201 in start
  File "/anaconda3/lib/python3.6/site-packages/glue/qglue.py", line 197 in qglue
  File "test.py", line 4 in <module>
Segmentation fault: 11