I use KDevelop3 and I love it. Kate is also alright, but it lacks a lot of the useful features I like about KDevelop3. I haven't really investigated many other GUI editors, simply because I don't need too!
Yes you can install source tarballs on Debian (it would be kinda stupid if you couldn't install them...). Why can't you download the source for Kdevelop? Try this and see what results you get:
Code:
apt-cache search kdevelop3
kdevelop3 - An IDE for Unix/X11 - development version
kdevelop3-data - An IDE for Unix/X11 - data
kdevelop3-dev - An IDE for Unix/X11 - development files
kdevelop3-doc - An IDE for Unix/X11 - documentation
kdevelop3-plugins - An IDE for Unix/X11 - development files