Master Page Template
OutSystems UI
OutSystems 6.0
I would really like to see something similar to ASP.NET Master Pages, where I can have a screen that other pages derive from, and when that master screen changes, so do the child pages. It is too easy to just use a 1 column table for page design because it is easy to use, but it really is the wrong way of doing things.

This is important to provide consistency across the web site.  If the style needs to change, it is done on the master, and all web pages using the master are automatically changed.
Wish granted!

In 6.0, you can specify a set of webblocks to be used for the layout of the page. In these you can define placeholders which correspond to empty spaces which you will only define when instantiating your pages.