Total Commander

Drag multiple folders with the mouse to an empty space in the tab header. If standard drag and drop keys (Ctrl, Alt, Shift) are pressed, the cursor changes properly (with one exception: if a modifier button is released, it goes to Add instead of going back to the original Shortcut), but the resulting behavior is always the same: a new inactive tab is being created.

Why not make the standard drop modes mean something, like activate the new tab (the first of the new tabs) on Add and close the source tab on Move?

A few days ago I've created this related thread.