_layoutChildren: function(/*String?*/ changedChildId, /*Number?*/ changedChildSize){
// summary:
// This is the main routine for setting size/position of each child.
// description:
// With no arguments, measures the height of top/bottom panes, the width
// of left/right panes, and then sizes all panes accordingly.
//
// With changedRegion specified (as "left", "top", "bottom", or "right"),
// it changes that region's width/height to changedRegionSize and
// then resizes other regions that were affected.
// changedChildId:
// Id of the child which should be resized because splitter was dragged.
// changedChildSize:
// The new width/height (in pixels) to make specified child
//example:
var bc = digit.byId(‘borderContainerId’);
var newSize = 150;
var childContentPaneId = ‘myPaneId’;
dojo.hitch(bc, bc._layoutChildren(‘childContentPaneId’,newSize));