I tend to have quite a few MXML application components in my applications. Some are for re-use purposes, some are templates, some are for wiring together MVC triads, others are just for organization. I haven't noticed any performance issues due to the "extra" containers, some of which may have a single child providing the actual desired layout. I tend not to subclass components in ActionScript (though I obviously have plenty of other ActionScript classes, and a couple of custom components)
I've also tended to use a lot of VBoxes and HBoxes in my layouts, though I'm using Canvases more and more. I've tended to make each MXML component a VBox, sometimes changing them after the fact. But I'd rather just have an "organizational" root component that can have a script block and do whatever non-layout binding stuff I want, with a single child responsible for layout. i.e. less editing of the first few lines in the file. Something like mx:Module without the layout rules, I guess. The reader would skim over the small-as-possible script block, and see a first tag indicating the type of layout. I see a couple of possibilities: - Make each app component a Canvas, meaning I can dive in and position children absolutely and with constraints, but it also has the nice default of sizing to contain children, just like Box. Will often be adding a single VBox or HBox child. This is the way I'm leaning, but I'm not sure how heavyweight Canvas is compared to Box. - Box (editing direction as needed, or adding canvases or nested boxes) - Custom. Is it possible to write a custom component that can be the root of an MXML file? It would be the simplest possible container, like a Box-of-one. I'm interested to hear the practices of others.
