eui.EditableText#prompt 在输入框聚焦后消失了

[DRL9]

version: 5.3.7
platform: web

let textFeild: eui.EditableText = new eui.EditableText();
textFeild.background = true;
textFeild.backgroundColor = 0x0;
textFeild.width = 217;
textFeild.height = 45;
textFeild.verticalAlign = 'middle';
textFeild.textAlign = 'center';
textFeild.prompt = '请输入内容';
textFeild.promptColor = 0xb9b4c2;
textFeild.size = 13;
textFeild.textColor = 0xb9b4c2;
textFeild.maxChars = 12;
this.once(
    egret.Event.ENTER_FRAME,
    () => {
        textFeild.setFocus();
        document.querySelector('canvas').click();
    },
    this
);
this.stage.addChild(textFeild);