private void SlidePanels(ITreeNode previousNode, ITreeNode newNode)
{
// Setup initial conditions.
HorizontalEdge direction = GetSlideDirection(previousNode, newNode);
// Slide off the old panel.
if (previousNode != null)
{
ListTreePanel oldPanel = GetOrCreatePanel(previousNode);
oldPanel.SlideOff(direction, null);
}
// Slide on the new panel.
ListTreePanel panel = GetOrCreatePanel(newNode);
panel.SlideOn(direction, null);
}