Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
 PackSplit.i3 by cgn & msm, coded Sat Nov  1 18:19:34 1986 
 Last modified on Mon Feb 24 13:54:47 PST 1992 by muller  
      modified on Thu Dec 12  1:07:03 PST 1991 by gnelson 
A TSplit.T is a parent window that giving its entire screen to one child at a time. The child being displayed is called the {\it current child}. The current child can be NIL, in which case the TSplit ignores all events.



  T <: Public;
  Private <: Split.T;
  Public = Private OBJECT METHODS
    <* LL.sup <= VBT.mu *>
    init(fickle := TRUE): T
The call v.init(fickle) initialize v as an empty TSplit.

If fickle is TRUE, then the shape of v will be the shape of its current child, or a VBT's default shape if the current child is NIL. If fickle is FALSE, then in each axis the size range of v will be the intersection of the size ranges of its children (if this intersection is empty, the children's maxsizes are increased until the intersection is non-empty). The preferred size of v is the the maximum of the preferred sizes of its children, projected into v's size range. If v has no children, its shape is a VBT's default shape.

PROCEDURE SetCurrent(v: T; ch: VBT.T)
RAISES {Split.NotAChild}; <* LL.sup = VBT.mu *>
Set the current child of v to be ch and mark v for redisplay.

PROCEDURE GetCurrent(v: T): VBT.T; <* LL.sup = VBT.mu *>
Return the current child of v.

PROCEDURE Cons(ch0, ch1, ch2, ch3, ch4: VBT.T := NIL;
  fickle := TRUE): T; <* LL.sup = VBT.mu *>
Create a TSplit with children ch0, ch1, ....
 Cons is equivalent to

      v := NEW(T).init(fickle);
      Split.AddChild(v, ch0, ch1, ch2, ch3, ch4);
      IF ch0 # NIL THEN SetCurrent(v, ch0) END;
      RETURN v

END TSplit.