Thanks for your reply. I tried setting w&h to 100% in the properties and it doesn't render properly in the designer, but does indeed flex in the generated app.
What about wrapping all controls in rows and columns by default. The example of more than one component in a column could be handled by a row with two columns in side the parent column.
This is one thing that made screen design in lightswitch so simple yet powerful. Everything on the screen was inside row and column containers and everything flexed by default.
Refer back to this idea: