property Node.BackgroundExtValue(Index as IndexExtEnum, Property as BackgroundExtPropertyEnum) as Variant
Specifies at runtime, the value of the giving property for specified part of the background extension.

Index as IndexExtEnum A Long expression that defines the index of the part that composes the EBN to be accessed / changed. 

The following screen shot shows where you can find Index of the parts:


The screen shot shows that the EBN contains 11 elements, so in this case the Index starts at 0 ( root element ) and ends on 10.

Property as BackgroundExtPropertyEnum A BackgroundExtPropertyEnum expression that specifies the property to be changed as explained bellow.
Variant A Variant expression that defines the part's value. The Type of the expression depending on the Property parameter as explained bellow.
Use the BackgroundExtValue property to change at runtime any UI property for any part that composes the EBN String Format. The BackgroundExtValue property has no effect if the BackgroundExt property is empty ( by default ). The idea is as follows: first you need to decide the layout of the UI to put on the object's background, using the BodyBackgroundExt property, and next ( if required ), you can change any property of any part of the background extension to a new value. In other words, let's say you have the same layout to be applied to some of your objects, so you specify the BodyBackgroundExt to be the same for them, and next use the BackgroundExtValue property to change particular properties ( like back-color, size, position, anchor ) for different objects.

You can access/define/change the following UI properties of the element:

For instance, having the BodyBackgroundExt on "bottom[50%,pattern=6,frame]"

we got:

so let's change the percent of 50% to 25% like  BackgroundExtValue(1,2) on "25%", where 1 indicates the first element after root, and 2 indicates the exClientExt property, we get:

In VB you should have the following syntax:

.BodyBackgroundExt = "bottom[50%,pattern=6,frame]"
.BackgroundExtValue(exIndexExt1, exClientExt) = "25%"