function winopen(toweburl,towebtext,width,height,scrollbars,resizable) {
var thiswidth = width;
var thisheight = height;
var endposition_x=(window.screen.width-thiswidth)/2
var endposition_y=(window.screen.height-thisheight)/2
window.open(toweburl,towebtext,"width="+width+",height="+height+",scrollbars="+scrollbars+",resizable="+resizable+",top="+endposition_y+",left="+endposition_x+"");
}