var Fenster = null;
function showimage(href,titel,w,h,scroll)
{
LeftPosition = (screen.width) ? (screen.width-w)/2 : 0;
TopPosition = (screen.height) ? (screen.height-h)/2 : 0;
settings ='height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',scrollbars='+scroll+',resizable=0'
Fenster = window.open(href,titel,settings)
}