[Inkscape-devel] just curious

A question for C++/gtkmm gurus:

Why do we have to have ALL widgets of a dialog declared in an .h file? They aren't usable outside the dialog anyway.

In general, while I appreciate many advantages of C++, the way it is used with gtkmm for Inkscape's dialogs is a major annoyance. A lot more typing in a lot more places than when using simple gtk where you can declare, create, and show a widget in a single spot in code. Is there some grand vision behind this that I'm missing?