Overflowing Property
True if the text inside the specified text frame doesn't all fit within the frame. Read-only Boolean.
expression.Overflowing
expression Required. An expression that returns a TextFrame object.
Example
This example checks to see whether the text in MyTextBox is overflowing its text frame. If so, the example adds another text box and links the two text boxes so that the text flows into the next one.
Set myTBox = ActiveDocument.Shapes("MyTextBox")
If myTBox.TextFrame.Overflowing = True Then
Set nextTBox = ActiveDocument.Shapes. _
AddTextbox(msoTextOrientationHorizontal, 72, 72, 100, 200)
MyTBox.TextFrame.Next = nextTBox.TextFrame
End If