Add licenses, add item delegate.
Implement Role_ImageRole in Model.
Implement item delegate.
If quit() is called, dequeue all remaining jobs.
Save and restore window state and geometry.

Great for demoing :-)
Ensure stable sorting order of items after sorting by priority.

Items will be shown in the reverse order of processing.
Add resource restriction for file loading.

Make cap configurable from the UI.
Log consumption in resource restrictions at level 4.
Implement shrinking the inventory when the thread cap is reduced.

It uses an exception to signal the thread to abort. Let's see if this is
the best option.
Implement setting the thread cap from the UI.
Add ImageListFilter to create individual lists per step.
Use individual list views for the different steps.
Implement configuring the processing caps form the view.
Assign resource restrictions to the processing steps.
Increase the inventory if the thread cap is raised while processing.
Connect slots to configure resource restrictions.