Miniature → Caching
Steps to reproduce:
1. Start DT in lightroom mode
2. Open any file in darkroom mode
3. Leave darkroom by pressing 'l'
4. Open any other file in darkroom mode
Notice that miniature (picture in top left corner) always shows previous picture before current picture is loaded and modules settings applied. Probably it is cached somewhere. Just showing nothing will do fine, showing previous picture is confusing.