Generally, border inherits the corner shape of the main gradient image. If some or all image corners are round (made by "Round It" or oval rectangle gradient), then the border would inherit respective round corners.
Force Round - by checking the box in "Round" column you would force the border corners to become round, while main image may have straight corners. Round corner radius and canvas color are inherited from "Round It" section of the main image.
|Here is a sample with forced Round corner for the border only.
Note: If straight corner for main image was also forced by selecting straight at the round selector: , then the force straight corner for main image would take precedence over force round for the border and the border corners would remain straight even with force Round.
Force Straight is an opposite to force round. Here you may selectively choose which border image corner would be shaped as round or straight.
|Here is a sample where main image has round corners, border image corners are inherited rounding, but bottom-left and bottom-right corners of the border image were shaped straight by checking respective boxes within Straight column:
Sync Radius. Normally round corners radius for border image is scaled with respect to the border width and always higher than the corner radius of the main image. If you need to keep the border image corners radius synced with the radius for main image corners, then check the respective box within "Sync Radius" column.
|Here is sample image without Sync Radius
|Same image with Sync Radius applied to all 4 corners.