div.moduleset {
  position: relative;
}

div.module {
  position: absolute;
  overflow: hidden;
}

form.modconfig {
  visibility: hidden;
  overflow: auto;
  position: absolute;
  z-index: +1000;
  font-family: monospace;
  background: white;
  border: 2px dashed black;
  padding: 2px;
}

div:hover > form.modconfig {
  visibility: visible;
}