Draw as border is completely opaque when size in negative

When an image widget is set to draw as border it will no longer render as a border if the size is negative. The widget appears completely opaque.

1. Open the editor
2. Create a new widget blueprint
3. Add an image to the designer tab
4. Set the Draw as setting to "Border"
5. Set Margins to 1, 1, 1, 1
6. Set the X size of the image widget to - 100

Result: The image no longer has a border but appears completely opaque
Expected: The Image would maintain its border when flipped to a negative size