First of all thank you for your script. It's another great work!
I noticed the following issue (Firefox only - it works ok in Chrome with Tampermonkey).
- (in a clean FF 51.0.1 x64 profile with only Greasemonkey 3.10 and your script v0.5.0 or any previous)
- open http://stackoverflow.com/
- mouseover on question links: notice that the script works ok.
- now switch to another tab (or open a new tab) via mouse or Ctrl+Tab while the preview is not visible(=move mouse away from last hovered link) and then return to the SE tab
- mouseoover on links: the script does't work anymore: there's no preview. Pressing F5 or Ctrl+F5 doesn't fix the problem. There's no related error in Browser Console.
The only solution is to close and reopen the SO tab.