button1= new Image();
button1.src = "./navi_01_info_over.jpg";
button2= new Image();
button2.src = "./navi_01_lab_over.jpg";
button3= new Image();
button3.src = "./navi_01_sky_over.jpg";
button4= new Image();
button4.src = "./navi_02_empf_over.jpg";
button5= new Image();
button5.src = "./navi_02_lab_over.jpg";
button6= new Image();
button6.src = "./navi_02_sky_over.jpg";
button7= new Image();
button7.src = "./navi_03_empf_over.gif";
button8= new Image();
button8.src = "./navi_03_info_over.gif";
button9= new Image();
button9.src = "./navi_03_sky_over.jpg";
button10= new Image();
button10.src = "./navi_04_empf_over.gif";
button11= new Image();
button11.src = "./navi_04_info_over.gif";
button12= new Image();
button12.src = "./navi_04_lab_over.gif";