From Xojo Documentation

Read-Only Property (As Boolean )
BooleanValue = aWebAnimator.ResizeSupported

New in 2010r4

Supported for all project types and targets.

Returns True if resize animation is supported by the web browser. If False, the Resize method does nothing.

Sample Code

Only use Resize if the browser supports it:

If Animator1.ResizeSupported Then
Animator1.Resize(Me, r.InRange(100, 300), Me.Height, 0.5)
End If