I am creating a container of JComponents which will look like a piano keyboard. The black keys look like this (Groovy)

def setBlackNotes(buttons) {
    def octaves = (int)(buttons.size() /  5)
    def gridLayout = new GridLayout(1, octaves*7);

    def blackNotePanel = new JPanel(gridLayout)
    this.add blackNotePanel
    def i = 0
    octaves.times {
        2.times {
            blackNotePanel.add buttons[i++]
        }

        blackNotePanel.add Box.createHorizontalBox()

        3.times {
            blackNotePanel.add buttons[i++]
        }

        blackNotePanel.add Box.createHorizontalBox()

    }
}

Which is just what I need, and looks like this:

but then I'd like to move this over to the right by half-a-key width. All of my attempts to move the blackNotePanel over by an arbitrary width -- wrapping it a BorderLayout, a MigLayout, etc. -- have failed or changed the spacing of the GridLayout radically.

Any suggestions on how to move this over to the right by an arbitrary amount in pixels?