question: public static Set < Window > updateUI ( ) { Set < Window > updated = new HashSet < Window > ( ) ; for ( Container c : s_windows ) { Window w = getFrame ( c ) ; if ( w == null ) continue ; if ( updated . contains ( w ) ) continue ; SwingUtilities . updateComponentTreeUI ( w ) ; w . validate ( ) ; RepaintManager mgr = RepaintManager . currentManager ( w ) ; Component childs [ ] = w . getComponents ( ) ; for ( Component child : childs ) { if ( child instanceof JComponent ) mgr . markCompletelyDirty ( ( JComponent ) child ) ; } w . repaint ( ) ; updated . add ( w ) ; } for ( Window w : s_hiddenWindows ) { if ( updated . contains ( w ) ) continue ; SwingUtilities . updateComponentTreeUI ( w ) ; w . validate ( ) ; RepaintManager mgr = RepaintManager . currentManager ( w ) ; Component childs [ ] = w . getComponents ( ) ; for ( Component child : childs ) { if ( child instanceof JComponent ) mgr . markCompletelyDirty ( ( JComponent ) child ) ; } w . repaint ( ) ; updated . add ( w ) ; } return updated ; }
target:  Update all windows after look and feel changes.