A duplicate of:

http://tweaker.userecho.com/topics/725-support-for-windows-10-fall-creators-update/

A duplicate of:

http://tweaker.userecho.com/topics/725-support-for-windows-10-fall-creators-update/

I can see no reason why hover will not show the thumbnails in all cases (active or not etc).

The thumbnails should be shown even when the program is not active. If it doesn't, perhaps it has something to do with your settings. Check your "Hovering" option in the tweaker, perhaps it's set to "Nothing"?

I'm not sure I understand the question. The "Open last window if inactive, otherwise open thumbnail preview" option doesn't affect hovering, you still should be able to hover to show the thumbnails.

Closing this. Leave a comment if you still have issues.

Please see the following blog post:

http://rammichael.com/7-taskbar-tweaker-for-windows-10-fall-creators-update

Error 209 means that 7+ Taskbar Tweaker could not place the necessary hooks in explorer. The error indicates a failure of the MinHook library which the tweaker uses.

One possible explanation is that there's a conflict between 7+ Taskbar Tweaker and another customization tool. Perhaps 7+ Taskbar Tweaker only runs successfully when it launches before the other tool.