if(document.images) {
  home_on = new Image();
  home_on.src = "gif/btn_home_on.gif";
  home_off = new Image();
  home_off.src = "gif/btn_home_off.gif";
  bridge_on = new Image();
  bridge_on.src = "gif/btn_bridge_on.gif";
  bridge_off = new Image();
  bridge_off.src = "gif/btn_bridge_off.gif";
	klaverjas_on = new Image();
	klaverjas_on.src = "gif/btn_klaverjas_on.gif";
	klaverjas_off = new Image();
	klaverjas_off.src = "gif/btn_klaverjas_off.gif";
	leisure_on = new Image();
	leisure_on.src = "gif/btn_leisure_on.gif";
	leisure_off = new Image();
	leisure_off.src = "gif/btn_leisure_off.gif";
	billiard_on = new Image();
	billiard_on.src = "gif/btn_billiard_on.gif";
	billiard_off = new Image();
	billiard_off.src = "gif/btn_billiard_off.gif";
	contact_on = new Image();
	contact_on.src = "gif/btn_contact_on.gif";
	contact_off = new Image();
	contact_off.src = "gif/btn_contact_off.gif";
	choir_on = new Image();
	choir_on.src = "gif/btn_choir_on.gif";
	choir_off = new Image();
	choir_off.src = "gif/btn_choir_off.gif";
	la_on = new Image();
	la_on.src = "gif/btn_la_on.gif";
	la_off = new Image();
	la_off.src = "gif/btn_la_off.gif";
	membership_on = new Image();
	membership_on.src = "gif/btn_membership_on.gif";
	membership_off = new Image();
	membership_off.src = "gif/btn_membership_off.gif";
	sint_on = new Image();
	sint_on.src = "gif/btn_sint_on.gif";
	sint_off = new Image();
	sint_off.src = "gif/btn_sint_off.gif";
}