如果您发现其他版本也有此BUG，可参照此方式进行修复，源代码中多了一句拦截mousedown事件的代码mousedownEvent.preventDefault()造成的。

Ext.define(‘Ext.override.grid.NavigationModel‘,{
    override:‘Ext.grid.NavigationModel‘,
    onCellMouseDown: function(view, cell, cellIndex, record, row, recordIndex, mousedownEvent) {
        var parentEvent = mousedownEvent.parentEvent,
            targetComponent = Ext.Component.fromElement(mousedownEvent.target, cell),
            column = mousedownEvent.position && mousedownEvent.position.column,
            cellEditing = view.grid.findPlugin(‘cellediting‘);

        if (targetComponent && targetComponent.isFocusable && targetComponent.isFocusable()) {
            if (!cellEditing || !cellEditing.editing) {
                targetComponent.focus();
            }
            if (column && column.stopSelection !== false) {
                return;
            }
        }
        if (!parentEvent || parentEvent.type !== ‘touchstart‘) {
            this.setPosition(mousedownEvent.position, null, mousedownEvent);
        }
    }
});

修复Extjs5.1.4表格设置enableTextSelection: true之后，文本仍然不能选择的BUG