自定义键盘, 切换到系统键盘后，系统键盘无法调起

@Entry  
@Component  
struct Index {  
  @State keyboardType: number = 0  
  @State text: string = ''  
  controller: TextInputController = new TextInputController()  
  @State flag:boolean = true  
  build() {  
    Column() {  
      Button('Set caretPosition 1')  
        .onClick(() => {  
          this.controller.caretPosition(1)  
        })  
      TextInput({ text: this.text, placeholder: 'input your word...', controller: this.controller })  
        .placeholderFont({ size: 14, weight: 400 })  
        .width(320).height(40)  
        .fontSize(14).fontColor(Color.Black)  
        .backgroundColor(Color.White)  
        .id('TextInput')  
        .customKeyboard(this.keyboardType == 0 ? this.buildCustomKeyboard() : null)  
        .defaultFocus(true)  
        .focusable(this.flag)  
    }  
    .backgroundColor(Color.Red)  
    .expandSafeArea([SafeAreaType.SYSTEM])  
    .width('100%')  
    .height('100%')  
  }  
  
  @Builder buildCustomKeyboard() {  
    Column({space: 10}) {  
      Row({space: 10}) {  
        Text('600')  
          .onClick(()=>{  
            this.text = '600'  
          })  
        Text('800')  
          .onClick(()=>{  
            this.text = '800'  
          })  
      }  
      .justifyContent(FlexAlign.SpaceAround)  
      .width('100%')  
      .layoutWeight(1)  
      Row({space: 10}){  
        Text('确认')  
          .onClick(()=>{  
            this.controller.stopEditing()  
          })  
        Text('中文')  
          .onClick(()=>{  
            this.keyboardType = 1  
            this.flag = false  
            setTimeout(()=>{  
              this.flag = true  
              focusControl.requestFocus('TextInput')  
            }, 2000)  
          })  
      }  
      .justifyContent(FlexAlign.SpaceAround)  
      .width('100%')  
      .layoutWeight(1)  
    }  
    .backgroundColor(Color.White)  
    .height(200)  
  } }