function _moveWorkingSetItem(paneId, fromIndex, toIndex) {
        var pane = _getPane(paneId);

        pane.moveWorkingSetItem(fromIndex, toIndex);
        exports.trigger("workingSetSort", pane.id);
        exports.trigger("_workingSetDisableAutoSort", pane.id);
    }
moves a working set item from one index to another shifting the items
after in the working set up and reinserting it at the desired location
@param {!string} paneId - id of the pane to sort
@param {!number} fromIndex - the index of the item to move
@param {!number} toIndex - the index to move to
@private