From the Inspector on Graphics, you can style each element's border individually, and also edit the borders properties like:
Style
Corners
Border Style
This control allows you to toggle between styling all borders at the same time, or each one of them individually.
(1) Control all borders at the same time.
(2) Control each border individually.
Style
(1) None Style
(2) Solid line
(3) Dashed line
(4) Dotted line
Size
(1) You can change the borders percentage to make it thinner or thicker
Corners
This control allows you to toggle between styling all corners at the same time, or each one of them individually.
(1) All corners.
(2) Each corner at a time.
(3) You can change the Corners percentage to make it rounder by increasing its radius.
This property applies to the following elements: