REnoise ViewBuilder API remove margin from buttons

no_margin.lua

    local function _b()
        return vb:horizontal_aligner {
            width = gridStepSizeW-2,
            mode = "center",
            vb:vertical_aligner {
                height = gridStepSizeH-2,
                mode = "center",
                vb:button {
                    width = gridStepSizeW,
                    height = gridStepSizeH,
                },
            },
        }
    end