function showImage(txtImage){
  switch(txtImage){
    case 'annotation':
      openWindow('annotation_screenshot.jpg');
      break;
    case 'extension':
      openWindow('extension_screenshot_2.jpg');
      break;
  }
}
	  
function openWindow(txtImage){
  window.open('images/' + txtImage,"_blank","toolbar=no, location=yes, directories=no, status=no, menubar=yes, scrollbars=yes, resizable=yes, copyhistory=yes, width=400, height=400")
}