function ButtonSel(Button,Sel) {
   ActImgName = Button.src;
   Pos = ActImgName.indexOf('_sel');
   if ((Sel != 0) & (Pos < 0)) {
     ActImgName = ActImgName.substr(0,ActImgName.length-4) + '_sel.gif';
     Button.src = ActImgName;
   }
   if ((Sel == 0) & (Pos > 0)) {
     ActImgName = ActImgName.substr(0,Pos) + '.gif';
     Button.src = ActImgName;
   }
}