title: In GTK+3, how do I get a drawingarea to respond to mouse events?
body: <p>In GTK+3, how do I get a drawing_area to respond to mouse events?</p>
  
  <p>In <strong><em>main()</em></strong> function I declared my <strong><em>drawing_area</em></strong>:</p>
  
  <pre><code>GtkWidget *drawing_area;
  </code></pre>
  
  <p>Then I connected the <strong><em>drawing_area</em></strong> with the mouse click signal:</p>
  
  <pre><code>g_signal_connect(drawing_area, "button-press-event", G_CALLBACK(clicked), NULL);
  </code></pre>
  
  <p>the function "clicked" is defined by:</p>
  
  <pre><code>static gboolean clicked(GtkWidget *widget, GdkEventButton *event, gpointer user_data)
  
      printf("Clicked! \n");
  
      return TRUE;
  }
  </code></pre>
  
  <p>The program runs and shows the drawing_area but when I click on it, no answer, nothing happens! Why is this happening?</p>