function create_images() {
		button1off=new Image(); button1on=new Image(); button1off.src="_img/button1off.gif"; button1on.src="_img/button1on.gif";
		button2off=new Image(); button2on=new Image(); button2off.src="_img/button2off.gif"; button2on.src="_img/button2on.gif";
		button3off=new Image(); button3on=new Image(); button3off.src="_img/button3off.gif"; button3on.src="_img/button3on.gif";
		button4off=new Image(); button4on=new Image(); button4off.src="_img/button4off.gif"; button4on.src="_img/button4on.gif";
		button5off=new Image(); button5on=new Image(); button5off.src="_img/button5off.gif"; button5on.src="_img/button5on.gif";
	}
	create_images();