The PStyleEdit code was really old and crappy. This an attempt
to clean up, fix bugs and improve the design completly.
Work in progress - There is still issues to fix, especially with undo & linebreaks.
Widgets can be connected to TBWidgetValue by the "connection" attribute in
resources (all TBWidgetValue should have unique names). Then the value
can always be set/get from TBWidgetValue instead of various pieces of UI.
Fixes ON_CHANGE event for TBEditField, TBInlineSelect.
Added handy GetText method that returns the string (with no status). Relying on RVO.