From Xojo Documentation

Property (As Integer )
aWebImageView.AlignVertical = newIntegerValue
IntegerValue = aWebImageView.AlignVertical

New in 2010r4

Supported for all project types and targets.

Controls the vertical alignment of the picture based on the class constant passed.

AlignVertical Class Constants

Class Constant Description
AlignDefault Default alignment is AlignCenter
AlignLeft Top alignment
AlignCenter Centered vertically
AlignRight Bottom alignment

Use this in conjunction with AlignHorizontal to position the image both horizontally and vertically in the control.