I am decided to learn gtk, but ran into trouble already with first example that I found on www.gtk.org's tutorials... Environment-variables must be wrong or something. I have installed gtk2 packages (at least I think all are included.. I installed gtk2 and gtk2-dev packages with yast. Now I try to compile an example code with gcc with: gcc base.c -o base 'pkg-config --cflags --libs gtk+-2.0' And I get: base.c:1:21: gtk/gtk.h: No such file or directory base.c: In function `main': base.c:6: error: `GtkWidget' undeclared (first use in this function) base.c:6: error: (Each undeclared identifier is reported only once base.c:6: error: for each function it appears in.) base.c:6: error: `window' undeclared (first use in this function) base.c:10: error: `GTK_WINDOW_TOPLEVEL' undeclared (first use in this function) How to proceed ? P_s