Layout params specified from resources should inherit any specified in widget constructor.
SetGravity should invalidate layout.

It's very likely that relayout is needed to apply the gravity.
Fix #7 TBButton should let height grow by default.

Fix is actually in TBTextField since that's the default content of a TBButton.

Introduced by d659761dd92a1ead13f4ffbe61e8610850fc6b35.
Added styled text to TBButton example.

Removed old comment. New way of doing things is to build like lego.
With widgets as building blocks, build whatever you want. Instead
of implementing everything :)