GTK+ vs GTK 2 vs GTKMM

[Dmitry Kruglov <info midisa org>]

I appeal to experienced programmers. What technology should I use? 

My requirements: 
1. I want (will) create very large applications. At least 50 windows. 
2. I want to use the visual editor for creating windows. 
3. I want to write code in C++ (compiler g++). 
4. I want to write programs only for the system Linux. 
5. I want to work with the database and use the Grid in different
windows: http://gtkextra.sourceforge.net/ 
6. I need the full documentation on the functions of the chosen technology. 
7. Technology should not have a lot of mistakes that, in the middle of
the project does not change the technology and do not redo the entire
project. 

I will be grateful for any information provided by my question. 

I totally get lost in the technology. I began to look different
instructions. In this
instruction: http://www.opennet.ru/docs/RUS/gtk_plus/x178.html 

Written, I quote: In version 2.0, the system signals moved from GTK to
GLib, so the functions and types in this section have the prefix "g_"
and not "gtk_". 

Why are all using old technology? Why use a function of GTK 1.2? 
For
example: http://tadeboro.blogspot.com/2009/09/glade3-tutorial-6-signals.html 
or http://www.micahcarrick.com/gtk-glade-tutorial-part-2.html 

Perhaps creating a new technology GTK 2, the authors tried to improve
the library?