User Interface Location: Click Document > Region Formatting

Watch this video to learn more about the region border:

In PTC Mathcad Prime 11.0.0.0, you can turn region borders on or off, and display them when they are not active or selected. You can choose to display the region border either individually or for a selected group. This applies to all regions that do not have borders displayed by default when inserted into a worksheet, including math, text, and plots.

With the region or regions selected, either use the right mouse button menu item Show border or go to the Document tab and use the Show Border button in the Region Formatting section. You can turn borders off using the same controls.