The Unfilled field of the BorderImageFill enumeration specifies that the middle of the container should not be filled with the border's background image. This is used in conjunction with the border-image-slice CSS property to control how the border image is applied to the element.
Use BorderImageFill.Unfilled when you want the border image to be applied only to the edges of the container, leaving the center area unfilled. This is useful for creating effects where the border image should not overlap or cover the content inside the container.
// Example of using BorderImageFill.Unfilled in a UI component
var myPanel = new Panel();
myPanel.Style.BorderImage = "url('border.png') 30 fill";
myPanel.Style.BorderImageFill = BorderImageFill.Unfilled;
// This will apply the border image to the edges of the panel without filling the center.