@update_function<EOL><INDENT>def _repack_and_regroup_children(self):<DEDENT>
if self.is_attached_to_gui:<EOL><INDENT>self._repack()<EOL>if self.__num_children > <NUM_LIT:0>:<EOL><INDENT>self.do_regroup_children()<EOL><DEDENT><DEDENT>
Resize and regroup the children of this widget if this widget is 
already attached to the GUI.  Otherwise, don't do anything.

Container widgets should call this method whenever a new child widget 
is attached.  

Before a widget is attached to the GUI, it can't have a size or a group 
because these attributes derive from a parent widget.  If any children 
are attached to the widget at this point, they cannot be given sizes or 
groups for the same reason.  Once the widget is attached to the GUI, it 
will be given a size and a group by its parent, then it will give sizes 
and groups to the children already attached to it.  If any children are 
attached after this point, they should be given a size and group right 
away.

Note that what happens when a child widget is attached to its parent 
depends on whether the parent is already attached to the GUI or not.  
If it is, the child is resized and regrouped (other children may be 
resized and regrouped at the same time).  Otherwise, nothing happens.  
This method handles this logic.  As long as container subclasses call 
this method each time a child is added or removed, their children will 
be properly sized and grouped no matter when they were attached.