I build a window with a beautiful dark brown colours contents. But the light gray border and title bar do not fit… Is there any method to change its colors, like I do with tabbedComponent and Buttons?
Read the documentation for the LookAndFeel class.
Actually, with DocumentWindow, you specify the colour (which is used for border and titlebar [and contents behind the content component]) in the constructor.
… that is assuming that you’re using DocumentWindow…