Auto Preview on app start with low piority

[Mannshoch]

The first thing I do after start of this app is hitting Preview.

In my opinion this could be done automatically.

• run with lower priority
• follow this rule:
  • create preview for ticked items which had the highest values on the last run first, until all ticked values are checked.
  • create preview for not ticked items. If some items ever calculated before, run these first.

[az0]

That makes sense.

Currently the preview and cleaning are single-threaded with the GUI, which has led to various problems and limitations. Once that is resolved, your idea would work better.