Well, Blender has quite a lot of nested menus and semi-hidden features. It was, in fact, the first popular free/libre desktop application to gain command search. GIMP followed suit years ago, now there's an avalanche of applications joining in: Olive, Inkscape, Krita (still in a branch, AFAIK), LibreOffice etc.

It's possible to move some of the nested menus into the main window. But as soon as you go anywere near filters, all hell breaks loose :)