what does "addNotify" really do ???

Hi,

Can someone explain to me what does the "addNotify()" command do
in Panel (or Applet).

I have a problem in NT platforms. My applet does not refresh an
 inner layed canvas. The same applet works fine on Unix and Win95
 platforms.

 Only when i added "addNotify()" to the applet start()
  it solved the refresh problem.
 But, to my poor luck it caused a SEGMENTATION FAULT(!) both in the
 Unix appletviewer and Netscape 3.0.

thanks,
Avi Kavas.