Show softkeyboard in AlertDialog type SYSTEM_ERROR or SYSTEM_ALERT

Question

I have an AlertDialog that comes over my active Activity (this is for a lock app) so i can block system buttons.

    public OverlayDialog(Activity activity, boolean backShouldWork, boolean justFinish) {
        super(activity, R.style.OverlayDialog);
        activ = activity;
        WindowManager.LayoutParams params = getWindow().getAttributes();
        params.type = WindowManager.LayoutParams.TYPE_SYSTEM_ERROR;
        params.dimAmount = 0.0F; // transparent
        params.width = MATCH_PARENT;
        params.height = MATCH_PARENT;
        params.gravity = Gravity.BOTTOM;
        getWindow().setAttributes(params);
        getWindow().setSoftInputMode(
                    WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE
        getWindow().setFlags(FLAG_SHOW_WHEN_LOCKED | FLAG_NOT_TOUCH_MODAL, 0xffffff);
        setOwnerActivity(activity);
        setCancelable(false);
    }

    protected final void onCreate(Bundle bundle) {
        super.onCreate(bundle);
        hideSystemUI(getWindow().getDecorView());
        sp = PreferenceManager.getDefaultSharedPreferences(getContext());
        editor = sp.edit();
        emergencyType = sp.getInt("emergency", 0);
        sequence = new ArrayList<>();
        mHandler = new Handler();
        mRunnable = new Runnable() {
            @Override
            public void run() {
                if (upPress && backPressed) {
                    activ.finish();
                }
            }
        };
        FrameLayout framelayout = new FrameLayout(getContext());
        framelayout.setBackgroundColor(0);
        EditText editText = new EditText(getContext());
        showKeyboard(editText);

        framelayout.addView(editText);
        setContentView(framelayout);
    }

    public void showKeyboard(final EditText ettext) {
        ettext.requestFocus();
        ettext.postDelayed(new Runnable() {
            @Override
            public void run() {
                InputMethodManager keyboard = (InputMethodManager) getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
                keyboard.showSoftInput(ettext, InputMethodManager.SHOW_FORCED);
            }
        } , 200);
    }

The problem is that the softkeyboard is not shown. I tried forcing the input method to be always visible, and to request focus for the edit text, but no luck Anyone encountered this problem ?