#include <gtk/gtk.h>GtkWidget *label;static gboolean release_resource( GtkWidget *widget,                                   GdkEvent  *event,                                   gpointer   data ){        gtk_main_quit ();        return FALSE;}void close_dialog_handler(GtkWidget *widget,gpointer data){	gtk_widget_destroy(GTK_WIDGET(data));	}void cb_set_font(GtkWidget *widget,gpointer data){	GdkColor color;		gchar *font_name=gtk_font_selection_dialog_get_font_name(GTK_FONT_SELECTION_DIALOG(data));		PangoFontDescription *font_desc=pango_font_description_from_string(font_name);	gtk_widget_modify_font(label,font_desc);	pango_font_description_free(font_desc);			gtk_widget_destroy(GTK_WIDGET(data));}void cb_show_font_dialog(GtkWidget *widget,gpointer data){	GtkWidget *font;		font=gtk_font_selection_dialog_new("choose your prefer font type...");		gtk_widget_show(GTK_FONT_SELECTION_DIALOG(font)->apply_button);		g_signal_connect(GTK_OBJECT(GTK_FONT_SELECTION_DIALOG(font)->ok_button),				"clicked",GTK_SIGNAL_FUNC(cb_set_font),(gpointer)font);        g_signal_connect(GTK_OBJECT(GTK_FONT_SELECTION_DIALOG(font)->apply_button),				"clicked",G_CALLBACK(cb_set_font),(gpointer)font);        g_signal_connect_swapped(GTK_OBJECT(GTK_FONT_SELECTION_DIALOG(font)->cancel_button),                                "clicked",G_CALLBACK(gtk_widget_destroy),(gpointer)font);        g_signal_connect(GTK_OBJECT(font),"destroy",                                G_CALLBACK(close_dialog_handler),(gpointer)font);		gtk_widget_show(font);}int main(int argc,char *argv[]){        GtkWidget *dialog;	GtkWidget *btn;        gtk_init (&argc, &argv);        	dialog= gtk_dialog_new();	gtk_window_set_title(GTK_WINDOW(dialog),"P19.7");	gtk_widget_set_size_request(dialog,350,150);		label=gtk_label_new("change font type and size");	gtk_box_pack_start(GTK_BOX(GTK_DIALOG(dialog)->vbox),label,FALSE,FALSE,0);	btn=gtk_button_new_with_label("Font...");	gtk_box_pack_start(GTK_BOX(GTK_DIALOG(dialog)->action_area),btn,FALSE,FALSE,0);       	g_signal_connect(G_OBJECT(btn),"clicked",                                        GTK_SIGNAL_FUNC(cb_show_font_dialog),NULL);        g_signal_connect(G_OBJECT(dialog),"delete_event",					G_CALLBACK(release_resource),NULL);        gtk_widget_show_all(dialog);        gtk_main();        return 0;}