Toolbar menu button issue

In order to making filing easier, I have created a toolbars with buttons pointing to folders on my hard drives. The goal is that no matter where I am in my file system, I can drag a file onto the appropriate button (pointing to the folder) and file it quickly, without having to navigate to that folder first. It works like a charm.

As you can understand, though, having a button for every folder leads to some really messy toolbars. So I decided to organize them in menus (on the toolbar). So, when I drag a file onto that toolbar menu, the menu drops down and then I can drop the file onto one of the items of that menu.

With menus, this scenario works well. However, with menu-buttons it doesn't. The problem is that when I drag a file onto a menu-button, the menu-button never expands (it never drops down.) I believe it should after a short delay when you drag on top of it and wait a little (or when the drag is on the drop-down arrow itself.) I think that would be the correct behavior.

Perhaps a feature request?