I have been trying to build an encapsulated class in the designer then use instances of it in various places in my designer project.
At the moment it is not easy to "expose" the properties of children in the top level instance. You have to override the initComponent and tweak things there.
I think it would be a great idea to allow code in values of properties to make this whole process easier.
Here is a simple example.
I have a Panel called EntityList. It contains a grid and a paging toolbar. Both of these children require the same store which is passed to the EntityList instance via a custom property (myStore). For efficiency I do not want to render the grid and paging toolbar with the wrong store then reconfigure them with the store set for this instance, so at the moment I am forced to override the initComponent and build my own children, settings the store for these two children.
However, if basic code could be used within property values, the grid and paging toolbar store properties could be set something like this...
where myStore is a custom property added to the EntityList panel. This would allow each instance to set a different store.
Of course having simple code in property values could have a whole host of other uses, not just exposing child properties at the top level, but it is a pretty useful one for OO development.