How to simply add a Separator like below to your custom gallery control?

1. Go to your Gallery (myGallery) and add a rectangle (mySeparator)

2. set the below properties on the rectangle

X= 2
Y= myGallery.TemplateHeight - mySeparator.Height
Width =  myGallery.TemplateWidth - 2 * mySeparator.X
Height= 2