There is a Style for each object:
DFrameStyle for
DFrames
BarStyle for Bars
('common' bars but also task Bar)
ButtonStyle for Buttons
MenuStyle for Menus
('common' Menus and context Menu)
Each Style will define the appearance and sometime the behaviors of objects.
Styles are easy to define but, as there is more than 200 methods for the 4 Styles, there is a Style checker that allow to check that all parameters used are corrects and consistent. See the DFrameAPI.checkStyles method.
Convention: In many time in the documentation it will be necessary to mention the "value set with the setXXX method". In short it will be called the "XXX" value:
Example
Instead of the "value set with the setBackgroundColor method" it will be used the "backgroundColor value".