Display display =  new  Display();
        Shell shell =  new  Shell(display, SWT.MAX);
        shell.setLayout( new  GridLayout());
         final  Button b1 =  new  Button(shell, SWT.NONE);
        b1.setText("b1");
        Button b2 =  new  Button(shell, SWT.NONE);
        b2.setText("b2");
         final  Button b3 =  new  Button(shell, SWT.NONE);
        b3.setText("b3");
        shell.setTabList( new  Control[]{b1, b2}); //вот так кнопка b3 не будет учавстовать в 
        shell.open();
         while  (!shell.isDisposed()) {
             if  (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();