Can not show popup window out of the keyboard view in Android Pie

Yes, I have solved my issue by changing my keyboard's layout file

I have added one dummy view above candidate view

like...

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <View
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toTopOf="@+id/rlPredictionView" />

    <RelativeLayout
        android:id="@+id/rlPredictionView"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@drawable/background_with_shadow_prediction_bar"
        android:visibility="visible"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent">

        ...

    </RelativeLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

than override this method in InputMethodService class

 @Override
    public void onComputeInsets(InputMethodService.Insets outInsets) {
        super.onComputeInsets(outInsets);
        outInsets.visibleTopInsets = candidateView.getRelativeView().getTop();
        outInsets.contentTopInsets = candidateView.getRelativeView().getTop();
    }

dummy view above rlPredictionView will set visibleTopInsets of the keyboard and in this area, the popup will show

this dummy view will allow accessing background view on touch so this will not visible to the user

Reference - https://stackoverflow.com/a/53326786/10989990