Cluttered menus

I have assembled quite a few plugins with my IntelliJ installation, and many of these add entries to some of the submenus of the main menu. In particular, the "File" > "New" menu is now so cluttered with entries that it doesn't even fit on one screen vertically (see screen shot).

Since I use most of these entries only occasionally (at best), I would like to either remove them from the submenu or add a new folder (e.g. named "UML") to it into which I could move all UML related entries.

I have tried using the "Menus and Toolbars" settings, but most of the items in my menu don't seem to be listed there at all (probably because they are provided by the plugins), and I also couldn't find out whether creating a new custom submenu/folder is possible.

Any suggestions on how I can shrink my submenus?