I’ve been meaning to do one of these for a while but never got the incentive until someone else started talking about it 
So I made a class that manages layouts for movie clips and other display objects. It lets you set position, size, center or top, right, bottom, or left constraints (similar to Flex). The following example shows basic usage and what behavior it can provide (source files available in link).
http://www.senocular.com/demo/Layout/LayoutWindows.html
There are a fairly good number of properties for a layout, and it’s use may not be 100% obvious, so I will probably need to provide some extra documentation, but the example should be a good place to get started. It uses most of the features and lets you see what the class is capable of.
Also, there is no GUI like in Flex, its all just AS 
Note: For the most up to date version of the classes, always use
http://www.senocular.com/flash/actionscript
