title: How to use the XGraphicsExposeEvent to draw something by Qt
body: <pre><code>typedef struct {
          int type;
          unsigned long serial;   /* # of last request processed by server */
          Bool send_event;        /* true if this came from a SendEvent request */
          Display *display;       /* Display the event was read from */
          Drawable drawable;
          int x, y;
          int width, height;
          int count;              /* if non-zero, at least this many more */
          int major_code;         /* core is CopyArea or CopyPlane */
          int minor_code;         /* not defined in the core */
  } XGraphicsExposeEvent;
  </code></pre>
  
  <p>we always can use the field [drawable] to paint something by GTK, like this :</p>
  
  <pre><code>GdkNativeWindow nativeWinId = (XID)((void*)(expose-&gt;drawable));
  ...
  ...
  // draw something by GdkNativeWindow with gtk APIs.
  </code></pre>
  
  <p>but how about Qt?</p>