When creating a new widget within a dashboard, you can choose a folder from wich tasks should be selected. It would be nice be able to add several folders in this view, and with an additional choice of selecting whether it should include the tasks that remain in either one of the folders, or just the ones that are in both.
Also, when dragging tasks to this widget in the dashboard, the task needs to be put in both folders. (Or maybe one could check/mark the folders that one wanted the tasks added to)
I know that I can achieve somewhat the same behaviour today, by doing a search for "folder:folderB" from within folderA and add this as a widget. But that gives me the problem that when dragging a task to this widget on a dashboard, the task will only be added to folderA. Also it is rather cumbersome to handle widgets this way.