gtk4: Right pane vbox cast as GTK_GRID()
gtk4-client gui_main.c:setup_widgets() has: "gtk_grid_set_column_spacing(GTK_GRID(vbox), 3);"
vbox really is (matching its name) GtkBox.
gtk4-client gui_main.c:setup_widgets() has: "gtk_grid_set_column_spacing(GTK_GRID(vbox), 3);"
vbox really is (matching its name) GtkBox.