please create derevatives for different widgets

[ilyapashuk]

please create different types for buttons, checkboxis, trees and other elements, like in walk.
it may be standalone structs without derevation from widget, but with converting functions.
mitchellh's mapstructure package can simplify conversion of widget specific properties to map[string]interface{}
and where documentation for existing available widgets can be found?
i hope i don't need to read sources of server module directly?