gcc editor.c -o fenster1 -Wall `pkg-config --libs gtksourceview-4 --cflags gtk+-3.0`
editor.c: In function ‘main’:
editor.c:27:11: warning: assignment to ‘GtkTextView *’ {aka ‘struct _GtkTextView *’} from incompatible pointer type ‘GtkWidget *’ {aka ‘struct _GtkWidget *’} [-Wincompatible-pointer-types]
  textview = gtk_source_view_new();
           ^
editor.c:46:25: warning: passing argument 1 of ‘gtk_widget_set_hexpand’ from incompatible pointer type [-Wincompatible-pointer-types]
  gtk_widget_set_hexpand(textview, TRUE);
                         ^~~~~~~~
In file included from /usr/include/gtk-3.0/gtk/gtkapplication.h:27,
                 from /usr/include/gtk-3.0/gtk/gtkwindow.h:33,
                 from /usr/include/gtk-3.0/gtk/gtkdialog.h:32,
                 from /usr/include/gtk-3.0/gtk/gtkaboutdialog.h:30,
                 from /usr/include/gtk-3.0/gtk/gtk.h:31,
                 from editor.c:1:
/usr/include/gtk-3.0/gtk/gtkwidget.h:1028:59: note: expected ‘GtkWidget *’ {aka ‘struct _GtkWidget *’} but argument is of type ‘GtkTextView *’ {aka ‘struct _GtkTextView *’}
 void     gtk_widget_set_hexpand          (GtkWidget      *widget,
                                           ~~~~~~~~~~~~~~~~^~~~~~
editor.c:47:25: warning: passing argument 1 of ‘gtk_widget_set_vexpand’ from incompatible pointer type [-Wincompatible-pointer-types]
  gtk_widget_set_vexpand(textview, TRUE);
                         ^~~~~~~~
In file included from /usr/include/gtk-3.0/gtk/gtkapplication.h:27,
                 from /usr/include/gtk-3.0/gtk/gtkwindow.h:33,
                 from /usr/include/gtk-3.0/gtk/gtkdialog.h:32,
                 from /usr/include/gtk-3.0/gtk/gtkaboutdialog.h:30,
                 from /usr/include/gtk-3.0/gtk/gtk.h:31,
                 from editor.c:1:
/usr/include/gtk-3.0/gtk/gtkwidget.h:1038:59: note: expected ‘GtkWidget *’ {aka ‘struct _GtkWidget *’} but argument is of type ‘GtkTextView *’ {aka ‘struct _GtkTextView *’}
 void     gtk_widget_set_vexpand          (GtkWidget      *widget,
                                           ~~~~~~~~~~~~~~~~^~~~~~
editor.c:55:44: warning: passing argument 1 of ‘gtk_widget_get_style_context’ from incompatible pointer type [-Wincompatible-pointer-types]
     context = gtk_widget_get_style_context(textview);
                                            ^~~~~~~~
In file included from /usr/include/gtk-3.0/gtk/gtkapplication.h:27,
                 from /usr/include/gtk-3.0/gtk/gtkwindow.h:33,
                 from /usr/include/gtk-3.0/gtk/gtkdialog.h:32,
                 from /usr/include/gtk-3.0/gtk/gtkaboutdialog.h:30,
                 from /usr/include/gtk-3.0/gtk/gtk.h:31,
                 from editor.c:1:
/usr/include/gtk-3.0/gtk/gtkwidget.h:1311:19: note: expected ‘GtkWidget *’ {aka ‘struct _GtkWidget *’} but argument is of type ‘GtkTextView *’ {aka ‘struct _GtkTextView *’}
 GtkStyleContext * gtk_widget_get_style_context (GtkWidget *widget);
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
editor.c:70:51: warning: passing argument 2 of ‘gtk_container_add’ from incompatible pointer type [-Wincompatible-pointer-types]
  gtk_container_add (GTK_CONTAINER (scrolled_win), textview);
                                                   ^~~~~~~~
In file included from /usr/include/gtk-3.0/gtk/gtkbin.h:33,
                 from /usr/include/gtk-3.0/gtk/gtkwindow.h:35,
                 from /usr/include/gtk-3.0/gtk/gtkdialog.h:32,
                 from /usr/include/gtk-3.0/gtk/gtkaboutdialog.h:30,
                 from /usr/include/gtk-3.0/gtk/gtk.h:31,
                 from editor.c:1:
/usr/include/gtk-3.0/gtk/gtkcontainer.h:150:22: note: expected ‘GtkWidget *’ {aka ‘struct _GtkWidget *’} but argument is of type ‘GtkTextView *’ {aka ‘struct _GtkTextView *’}
        GtkWidget    *widget);
        ~~~~~~~~~~~~~~^~~~~~