[gtkmm] gtkmm questions

[Todd Fisher <taf2 lehigh edu>]

I've been working on building a C++ based web crawler. Needless to say 
it processes a tremendous
amount of text from all different locals.  I have a few questions 
regarding gtkmm or i guess glibmm.
1. do i need to link to all gtkmm or can i just link to glibmm?
2. I was reading in the online documentation about ustring and wondered 
why a method like
   ustring Glib::ustring::uppercase()const
is necessary if its resulting  string may not have the same number of 
characters?  I'm sure there is
a technical reason for this, but on the surface it seems rather destructive.

3. The documents also suggest that there is a particular high 
performance cost in using the compare methods of ustring and yet
alludes that strings can safely be stored in std::string's.  What about 
the cost of conversion from std::string to Glib::ustring?

thank you very much and my apologies in advance if these questions have 
already been answered.

-todd