This parameter is used, in order to define a sensitive area in the applet. The Button reacts then only to mouse clicks within this area. A list of XY coordinates is used to describe a polygon which defines this sensitive area. The coordinates are relative to the left upper corner of the applet. Hence, the PictureButton reacts only on clicks on the bell button.
All values refer to the left upper corner of the applet.
If this parameter is not used, then the pictures are centered in the applet. This image as well as the other images may be specified in either GIF or JPG format. Transparent GIF's are supported. This parameter is optional. If it is missing, then only the applet background is displayed, but the complete functionality is useable.