Anchors
Anchor Points are points, circles, or lines that are attached (anchored), evenly spaced, to an element. If the element moves or changes length, the anchor points remain attached to it and are redistributed as appropriate.
Select the Anchor tool on the ribbon or press Ctrl + Alt + P.
With the Anchor tool active, hover over the element where you want to attach anchor points. A preview will show with the current Anchor tool settings. The Element Tool Window will show your tool options. Press Tab or click in a field to edit the values. Tools available will only be the types allowed for that Style. Click the element to add the anchors or click the Create or Remove buttons. Anchors may also be added, removed, or edited from the element’s Element Tool Window.
You can also add anchors by selecting an element and then use the Element Tool Window.