In the lister layout, I can select to show e.g. the metadata pane and the viewer pane.
I would absolutely love to have another pane that displays the contents of a fixed folder.
The bottom lister of my dual display is almost always my downloads folder. I do a lot of work originating from that folder. It would be great if I could pin that folder as a separate pane to the top right (above the metadata and viewer panes).
The folder that my new "Folder Pane" displays is static and configured somewhere in the options.
There is no need to show it in any folder tree.
I'd expect the behavior to be the same as a tab "Locked (allow folder changes)".
Optionally, to save window space, the folder pane could be a "lite"-version of the standard folder tab. None of the customizability etc. is required - display folders/files and the columns. Keep it simple.
Super optionally, it would be a plus if the number of Folder Panes was configurable, so that I can have more than one (within reason). I'd personally have one for downloads, one for a temp-folder and maybe even a third for a output folder (from a development project).