button1_off=new Image();button1_on=new Image();button1_off.src='images/button_1a.gif';button1_on.src='images/button_1b.gif';
button2_off=new Image();button2_on=new Image();button2_off.src='images/button_2a.gif';button2_on.src='images/button_2b.gif';
button3_off=new Image();button3_on=new Image();button3_off.src='images/button_3a.gif';button3_on.src='images/button_3b.gif';
button4_off=new Image();button4_on=new Image();button4_off.src='images/button_4a.gif';button4_on.src='images/button_4b.gif';
button5_off=new Image();button5_on=new Image();button5_off.src='images/button_5a.gif';button5_on.src='images/button_5b.gif';