Returns or sets the horizontal distance (in points) between the end of the callout line and the text bounding box. Read/write Single.
Example
This example sets the distance between the callout line and the text bounding box to 3 points for shape one on myDocument. For the example to work, shape one must be a callout.
Set myDocument = ActivePresentation.Slides(1)
myDocument.Shapes(1).Callout.Gap = 3