Installing GTK3

[Nick Lehmann <nickmann97 gmail com>]

Hello everyone,

I'm a German guy with Perl experience and a little problem. I want to
install the Gtk3-perl-module. I installed the module and also
Glib::Object::Introspection. 
But when I tried out the example from https://metacpan.org/module/Gtk3,
I only got the error message:

Can't locate object method "_register_boxed_synonym" via package "Glib::Object::Introspection"

Then I installed Glib-Object-Introspection-0.015, which required the Glib version 1.28, the latest version.
After that I downloaded und extracted Glib, but while executing the command "perl Makefile.PL" I got the 
message

Package gobject-2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `gobject-2.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'gobject-2.0' found
 at Makefile.PL line 58.
*** can not find package gobject-2.0 >= 2.0.0
*** check that it is properly installed and available in PKG_CONFIG_PATH
 at Makefile.PL line 58

I had all dependencies installed. I couldn't find gobject with a "find /", and also couldn't find this file 
in the internet.

Can anybody help me?
Thanks
Nick