Groups would be much easier to work with in the thumbnail and preview views if you could see which items are in a particular group when it is expanded. Since there are no indications if an item is in a group or not, it is difficult to determine if I need to add something to a group, if it's already in a group, or if it's in the correct group. I'm imagining a colored background or border to indicate group boundaries.
*** This bug has been marked as a duplicate of bug 381414 ***
Enhancement: Grouped Items Usability Improvements This update introduces significant usability improvements for grouped items in digiKam: - Visual Highlighting for Open Groups: Previously, only closed groups were visually distinguished by a decorative border around the thumbnail of the stack's representative image. Now, each item within an open group is also highlighted with a colored border, ensuring better visual consistency and making it easier to identify group members at a glance. - Tree-View in Image Properties: The Image Properties right sidebar tab now supports a tree-view display for grouped items. Users can expand or collapse group stacks on demand, providing a more intuitive and flexible workflow. For a visual demonstration of these features in action, check out the screencast of digiKam 8.9.0: https://i.imgur.com/9QZ8kZw.mp4