Why did my DialogFragment not appear in full screen in Android 11?

Question

I have a dialogfragment I am using to select from a list. I have this in fullscreen, and it has always worked prior to 11/ API 30. However, now in 11 it started appearing with the classic "not in fullscreen" look, where you can see the layout behind it on all four sides.

I got it working again by overriding the onCreateDialog method, see below. In that method, I basically duplicate the calls I already make in onStart().

My question is WHY DID I HAVE TO DO THIS? It works fine prior to version 11/30, and i haven't found any documentation that mentions any changes related to this in 11.

New method I had to add:

@Override
public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
    final Dialog dialog = super.onCreateDialog(savedInstanceState);
    dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
    dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
    dialog.getWindow().setLayout(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
    return dialog;
}

My onStart that made the window appear normal prior to 11:

public void onStart() {
    super.onStart();
    Window window = getDialog() != null ? getDialog().getWindow() : null;
    if (window != null) {
        if (windowAnimStyle > 0) {
            window.getAttributes().windowAnimations = windowAnimStyle;
            }
            window.clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
            window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            window.addFlags(WindowManager.LayoutParams.FLAG_LAYOUT_INSET_DECOR);
            window.addFlags(WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN);

            window.setLayout(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
            window.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        }
    }

Answer 1

this works for me on the sdk 30

<style name="FullScreenDialogStyle">
    <item name="android:windowFullscreen">true</item>
    <item name="android:windowIsFloating">false</item>
</style>

override onCreate in your DialogFragment subclass

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setStyle(STYLE_NO_TITLE, R.style.FullScreenDialogStyle)
}