Is it possible to drag a folder in a current DOPUS window to the right-side of the window pane to force it to split/dual display with the current folder and the dragged folder?
If not, I think that be a cool feature to add in the future.
Cheers,
DMDComposer
Ctrl + Double-Click, or Middle button double-click (without Ctrl) will do that by default. You can also set up context menus, hotkeys or buttons to do the same thing. (Go FROMSEL OPENINDUAL)
For drag & drop itself, you can drag a folder to the tab bar to open it on either side, but only if the dual display is already open. The other methods will open it if it isn't already open.