Main window: Image area: Fix stock icon displaying

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Main window: cosmetic: verbose

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Merge branch 'unstable' into wip-remake-scan-process

Conflicts:
	src/paperwork/frontend/mainwindow/__init__.py

Signed-off-by: Jerome Flesch <jflesch@gmail.com>