Steps to reproduce
- visit http://localhost:8181/wiki/Middle_English on the Vector desktop site with reference previews enabled.
- Hover over "[4]".
- In the reference preview that appears, hover over "[3]".
Expected results
- Reference preview should remain unchanged.
Actual results
- Reference preview disappears.
Environments observed
- Browser version: Chromium v71.0.3578.98
- OS version: Ubuntu v18.10
- Device model: Desktop
- Device language: English
- Git commit: fb56a2e