我可以使用配置anchor: true和defaultAlign: 't100-r30'将工具提示的位置固定在面板的右上角
下面是更新后的小提琴代码：

var someButton = Ext.create({
    xtype: 'button',
    text: 'Some button'
});

Ext.application({
    name: 'Fiddle',

    launch: function () {
        Ext.create({
            id: 'parentPanel',
            height: 300,
            xtype: 'panel',
            title: 'parentPanel',
            items: [{
                html: "<span style='font-size:20px;'>Hover mouse on this green panel</span>",
                bodyStyle: "background: lightgreen;",
                xtype: 'panel',
                height: "50%",
                width: "70%",
                padding: "5 5",
                cls: 'overlayMenuCls'
            }, {
                html: "<span style='font-size:20px;'>Hover mouse on this blue panel</span>",
                bodyStyle: "background: lightblue;",
                xtype: 'panel',
                height: "50%",
                width: "70%",
                padding: "5 5",
                cls: 'overlayMenuCls'
            }],
            listeners: {
                boxready: {
                    fn: 'onPanelBeforeRender',
                    scope: this
                }
            },
            layout: "vbox",
            renderTo: Ext.getBody()
        });
    },

    onPanelBeforeRender: function (view) {
        var me = this;
        console.log(view);
        var tip = Ext.create('Ext.tip.ToolTip', {
            target: view.el,
            delegate: '.overlayMenuCls',
            //             trackMouse: true,
            anchor: true,
            dismissDelay: 0,
            defaultAlign: 't100-r30',
            items: [{
                xtype: 'button',
                text: 'menu',
                cls: "overlayMenuCls",
                menu: {
                    items: [{
                        text: 1
                    }, someButton]
                },
                listeners: {
                    mouseover: function () {
                        tip.isItemOver = true;
                    },
                    mouseout: function () {
                        tip.isItemOver = false;
                    }
                }
            }],
            listeners: {
                beforeshow: function (tip) {
                    var button = tip.items.items[0];
                    var menu = button.menu;
                    console.log(tip.items.items[0]);
                },
                beforehide: function (tip) {
                    if (tip.isItemOver) {
                        return false;
                    }
                }
            }
        });
    }
});