rotateSelected (cw, step) {
    if (!this.selectedElement || this.multiselected) {
      return
    }
    if (!cw) {
      step *= -1
    }
    const angle = Number.parseFloat($id('angle').value) + step
    this.svgCanvas.setRotationAngle(angle)
    this.topPanel.updateContextPanel()
  }
@param {0|1} cw
@param {Integer} step
@returns {void}