     
     /**
      *  Returns 1.0 if the specified index is completely in view, 0.0 if
-     *  it's not, and a value in between if the index is partially 
-     *  within the view.
-     * 
-     *  An index is "in view" if the corresponding non-null layout element is 
-     *  within the horizontal limits of the layout target's scrollRect
-     *  and included in the layout.
-     *  
-     *  If the specified index is partially within the view, the 
+     *  it's not, or a value between 0.0 and 1.0 that represents the percentage 
+     *  of the if the index that is partially in view.
+     * 
+     *  <p>An index is "in view" if the corresponding non-null layout element is 
+     *  within the horizontal limits of the container's <code>scrollRect</code>
+     *  and included in the layout.</p>
+     *  
+     *  <p>If the specified index is partially within the view, the 
      *  returned value is the percentage of the corresponding
-     *  layout element that's visible.
-     * 
+     *  layout element that's visible.</p>
+     *
+     *  @param index The index of the column.
+     * 
+     *  @return The percentage of the specified element that's in view.
      *  Returns 0.0 if the specified index is invalid or if it corresponds to
-     *  null element, or a ILayoutElement for which includeInLayout is false.
-     * 
-     *  @return the percentage of the specified element that's in view.
-     *  @see firstIndexInView
-     *  @see lastIndexInView
+     *  null element, or a ILayoutElement for which 
+     *  the <code>includeInLayout</code> property is <code>false</code>.
      *  
      *  @langversion 3.0
      *  @playerversion Flash 10

import spark.layouts.supportClasses.LinearLayoutVector;

/**
 *  The HorizontalLayout arranges the layout elements in a horizontal sequence,
 *  left to right, with optional gaps between the elements and optional padding
 *  around the sequence of elements.
 *
 *  <p>During measure(), the default size of the container is calculated by
 *  accumulating the preferred sizes of the elements, including gaps and padding.
 *  When requestedColumnCount is set, only the space for that many elements
 *  will be measured, starting from the first element.</p>
 *
 *  <p>During updateDisplayList(), the width of each element is calculated
 *  according to the following rules, listed in their respective order of
 *  precedence (element's minimum width and maximum width are always respected):
 *  <ul>
 *    <li>If variableColumnWidth is false, then set the element's width to the
 *    value of the columnWidth property.</li>
 *
 *    <li>If the element's percentWidth is set, then calculate the element's
 *    width by distributing the available container width between all
 *    elements with percentWidth setting. The available container width
 *    is equal to the container width minus the gaps, the padding and the
 *    space occupied by the rest of the elements. The element's precentWidth
 *    property is ignored when the layout is virtualized.</li>
 *
 *    <li>Set the element's width to its preferred width.</li>
 *  </ul>
 *
 *  The height of each element is calculated according to the following rules,
 *  listed in their respective order of precedence (element's minium height and
 *  maximum height are always respected):
 *  <ul>
 *    <li>If verticalAlign is "justify" then set the element's height to the
 *    container height.</li>
 *
 *    <li>If verticalAlign is "contentJustify" then set the element's height
 *    to the maximum between the container's height and all elements' preferred
 *    height.</li>
 *
 *    <li>If the element's percentHeight is set, then calculate the element's
 *    height as a percentage of the container's height.</li>
 *
 *    <li>Set the element's height to its preferred height.</li>
 *  </ul>
 *
 *  The horizontal position of the elements is determined by arranging them
 *  in a horizontal sequence, left to right, taking into account the padding
 *  before the first element and the gaps between the elements.
 *
 *  The vertical position of the elements is determined by the layout's 
 *  verticalAlign property.</p>
 *
 *  @langversion 3.0
 *  @playerversion Flash 10

     *  The vertical alignment of layout elements.
     * 
     *  <p>If the value is <code>"bottom"</code>, <code>"middle"</code>, 
     *  or <code>"top"</code> then the layout elements are aligned relative 
     *  to the container's <code>contentHeight</code> property.</p>
     * 
     *  <p>If the value is <code>"contentJustify"</code> then the actual
     *  height of the layout element is set to 
     *  the container's <code>contentHeight</code> property. 
     *  The content height of the container is the height of the largest layout element. 
     *  If all layout elements are smaller than the height of the container, 
     *  then set the height of all the layout elements to the height of the container.</p>
     * 
     *  <p>If the value is <code>"justify"</code> then the actual height
     *  of the layout elements is set to the container's height.</p>
     *
     *  <p>This property does not affect the layout's measured size.</p>
     *  
