HasChildShapeRange returns incorrect values

Chris King reported this one in the PowerPoint Newsgroup. This bug affects PowerPoint 2007 and 2003 at least, and may affect earlier versions.

Problem

Although HasChildShapeRange is listed as boolean in the object browser, when HasChildShapeRange is True, its value is 1, not -1. Consequently, IF statements may not work as expected.

To reproduce the problem

To illustrate the problem, put a couple of shapes on a slide and group them, then select one of the group. That makes HasChildShapeRange true. (ChildShapeRange returns the members of a group that are selected.) Insert
the following into a module, and run it:

Sub Play()
   With ActiveWindow.Selection
      If .HasChildShapeRange Then
         Debug.Print "Yes"
      Else
         Debug.Print "No"
      End If
      If .HasChildShapeRange = True Then
         Debug.Print "Yes"
      Else
         Debug.Print "No"
      End If
      If .HasChildShapeRange = False Then
         Debug.Print "No"
      Else
         Debug.Print "Yes"
      End If
      If Not .HasChildShapeRange Then
         Debug.Print "No"
      Else
         Debug.Print "Yes"
      End If
   End With
End Sub

Because HasChildShapeRange is true, the expected output would be

Yes, Yes, No, No

The actual output is

Yes, No, Yes, No

The expression

If .HasChildShapeRange = True Then

evaluates as false because 1 is not equal to -1 (the value of True).

The expression

If Not .HasChildShapeRange Then 

always evaluates as True. (If HasChildShapeRange is False, it equals 0; "Not 0" is -1, or True. If HasChildShapeRange is True, it equals 1; "Not 1" is also True. Only "Not -1" is 0, or False.)

Workaround

Use

If .HasChildShapeRange Then

to test if the expression is True.

Use

If .HasChildShapeRange = False Then

to test if it is False.

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