/// <summary>Moves the focus to the next element as defined by tabindex.
/// All elements with an explicit tabindex are defined as being before all
/// elements which don't have an explicit tabindex.</summary>
/// <returns>True if anything happened.</returns>
public bool TabNext()
{
// - From the current focused element, we check all elements after it to see which
// has the 'closest' tabIndex to currentIndex.
// - If there are no immediate matches, we wrap around the DOM and continue searching
// - If there is no current focused element, we start at very top and don't wrap at all.
// These track the current best found element.
int bestSoFar = int.MaxValue;
HtmlElement best = null;
// Get the current focused element:
HtmlElement focused = htmlActiveElement;
if (focused == null)
{
// Haven't got one - hunt for a node with a tabindex first:
body.SearchChildFocusable(null, true, 0, ref bestSoFar, ref best);
if (best == null)
{
// Find the first focusable node:
body.SearchChildFocusable(null, true, -1, ref bestSoFar, ref best);
}
}
else
{
best = focused.GetFocusedNext();
}
if (best != null)
{
// Focus it now:
best.focus();
return(true);
}
return(false);
}