When Scaling in and out in the UMG blueprints with an image applied to an image widget that is set to border as it's "Draw as" selection the image does not scale correctly.
EDIT: The UI should prevent setting both sides of a margin to 1's. The most two margins can have on opposite sides at the same time is 0.5.
1. Open UE4 Editor with starter content
2. Create a new blueprint widget by right clicking in content browser
>user interface>Blueprint Widget
3. Make sure that Designer tab is selected in upper right corner
4. Drag an image widget from Palette into viewport
5. Select the widget by clicking in the center of it.
6. In the details tab under appearance expand Brush
7. Click to expand the drop down menu next to image.
8. Select M_Rock
9. Click, Change the material domain.
10. Set Draw as, under he Appearance drop down, to "Border"
11. Under Margin set Left,Top,Right, and Bottom to 1
12. Zoom in and out
Black border stays the same size, regardless of distance from camera.
Scale of border stays relative, regardless of camera distance.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-4630 in the post.