_onAddText(event) {
    /**
     * The event when 'TEXT' drawing mode is enabled and click non-object area.
     * @event ImageEditor#addText
     * @param {Object} pos
     *  @param {Object} pos.originPosition - Current position on origin canvas
     *      @param {Number} pos.originPosition.x - x
     *      @param {Number} pos.originPosition.y - y
     *  @param {Object} pos.clientPosition - Current position on client area
     *      @param {Number} pos.clientPosition.x - x
     *      @param {Number} pos.clientPosition.y - y
     * @example
     * imageEditor.on('addText', function(pos) {
     *     console.log('text position on canvas: ' + pos.originPosition);
     *     console.log('text position on brwoser: ' + pos.clientPosition);
     * });
     */

    this.fire(events.ADD_TEXT, {
      originPosition: event.originPosition,
      clientPosition: event.clientPosition,
    });
  }
Mousedown event handler in case of 'TEXT' drawing mode
@param {fabric.Event} event - Current mousedown event object
@private