I checked my Ubuntu (using Synaptic Package Manager), it has libgtk2.0-dev installed.
@TCH
Does your system have libgtk2.0-dev properly installed?
Yes, but since
libgtk2.0-dev alone is not enough, i had to install
libgtk2.0-dev:i386, but due the Debian team's brainless package organizing, it collides with
libgtk2.0-dev, so i had to install the i386 version by hand; extracting and copying. (The header files are the same (hence the collosion), but some different binaries are also inside the packages, and Debian team did not take the effort to separate the header files from them. And since
lazarus-project itself depends on
libgtk2.0-dev, i cannot remove it to install
libgtk2.0-dev:i386.)