You can also code them yourself using the tutorial found here: Columns and Widgets Tutorial.
Or in some cases, you may have your own custom widget layout (here made with this Code Generator).
In these cases, you may want to be able to use one of the nice advanced feature of "Plus" which is the Widget Height Equalization.
Xtreme lets you do just that using the method described in Item 2 of this Tutorial.
Resize your browser to observe equalization through changes of layouts.