Maybe this was just me.
Two panels open.
- Text Pane (2 Panels + Info Panel)
- Passage Guide.
- Working in Program Settings. Meant to close tab. Clicked close panel instead (red x)
- Text Pane closed.
- Remembered that if I closed Passage Guide that Text Pane would reopen.
- So I did and Text Pane immediately reopened but spinning pizza appeared and didn't stop after short wait.
- Went to Dock icon. "Not responding". Forced Quit.
Now that's twice in a very short time. Okay, it was my stupid click error that started it off. 
