<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE language SYSTEM "klayout_doc.dtd">

<doc>

  <title>Telling Used From Unused Layers</title>
  <keyword name="Layer properties"/>
  <keyword name="Used layers"/>

  <p>
  In some applications, the layer list will grow very large and keeping track
  of the important layers may be hard. KLayout provides support for that task 
  in two ways: KLayout checks whether a layer carries any information 
  and displays the layers in a different way in the layer list, if it is empty.
  </p>

  <p>
  Two ways of checking the information content of a layer are provided: either a layer is said to be 
  empty if the current cell does not have any shapes on it. Alternatively, a layer can be 
  identified to be empty by checking if any shape is shown in the current view (more precisely if
  any shape's bounding box overlaps with the current view rectangle). The latter mode can be selected
  in the layer list's context menu with the option "Test For Shapes in View".
  </p>

  <p>
  If a layer is determined to be empty, it is either grayed out or it is now shown at all.
  The latter option keeps the layer list short and is selected with "Hide Empty Layers" from the
  layer list's context menu.
  </p>

</doc>

