Unable to compile theme

[adueppen]

I was following the guide for compiling from source, and after running make, I got this error:

valac --pkg gtk+-3.0 elegance-colors-prefs.vala -o elegance-colors-prefs
/home/admin/Github/elegance-colors-master/elegance-colors-prefs.vala.c:7:21: fatal error: gtk/gtk.h: No such file or directory
 #include <gtk/gtk.h>
                     ^
compilation terminated.
error: cc exited with status 256
Compilation failed: 1 error(s), 0 warning(s)
make: *** [elegance-colors-prefs] Error 1

I don't know any Vala or C at all, so I don't really know what's happening.

[adueppen]

update: after installing some GTK3 related packages (I'm on Ubuntu, by the way) now I get this error:

valac --pkg gtk+-3.0 elegance-colors-prefs.vala -o elegance-colors-prefs
/home/alex/Github/elegance-colors-master/elegance-colors-prefs.vala.c: In function ‘main’:
/home/alex/Github/elegance-colors-master/elegance-colors-prefs.vala.c:10092:2: warning: ‘g_type_init’ is deprecated (declared at /usr/include/glib-2.0/gobject/gtype.h:667) [-Wdeprecated-declarations]
  g_type_init ();
  ^