isDisabled (sel, params) {
    const selectionState = params.selectionState
    const isBlurred = params.editorSession.isBlurred()
    // TODO: Container selections should be valid if the annotation type
    // is a container annotation. Currently we only allow property selections.
    if (isBlurred || !sel || sel.isNull() || !sel.isAttached() || sel.isCustomSelection() ||
        sel.isNodeSelection() || sel.isContainerSelection() || selectionState.isInlineNodeSelection) {
      return true
    }
    return false
  }
Checks if command couldn't be executed with current selection.

    @param {Array} annos annotations
    @param {Object} sel selection

    @returns {Boolean} Whether or not command could be executed.