Imagine sorting the items from one folder (say an inbox folder) into other folders. With a somewhat elaborated hierarchical folder structure, it is necessary to browse a bit to find potential target folders. For this, I frequently have to click on a potential target folder to see what is in there and decide if the item to be sorted belongs there. But doing this, the view on the 'source' folder is lost.

Would it be possible to create multiple windows for the left pane with different 'views' (just as you can with notes), such that one window could keep the view on folder A, and another window could be used to browse the folder structure for the target folder(s) B ?