Allow the width of one object to use another object's width

In order to make it easy to develop a box (A) to be the size of a text box (B) by making the width of box A a function (dynamic data) of box B.

This would be especially useful for things like messaging apps that currently use HTML code blocks to make the width responsive to the text. It could also be used to make it easier for apps to become responsive to different view windows.