footer
Since UXP v3.0
The <footer>
element is used in dialogs to help align buttons to the right-side of a dialog. You aren't required to use this element, and you can override any styles if you so choose.
See: https://developer.mozilla.org/en/docs/Web/HTML/Element/footer
Example
Copied to your clipboard<dialog><form method="dialog"><sp-heading>A heading</sp-heading><sp-divider size="large"></sp-divider><sp-body>Hello!</sp-body><footer><sp-button>Close</sp-button></footer></form></dialog>
Copied to your clipboarddocument.querySelector("dialog").uxpShowModal({size: {width: 480, height: 360}});