Program: 33123
Project: 33123
Buggy source:
@Override protected void onCreate(Bundle savedInstanceState){
  super.onCreate(savedInstanceState);
  requestWindowFeature(Window.FEATURE_NO_TITLE);
  getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD| WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED| WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
  getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_FULLSCREEN | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
  setContentView(R.layout.activity_call);
  btnHangup=(ImageButton)findViewById(R.id.button_hangup);
  btnHangup.setOnClickListener(this);
  btnAnswer=(ImageButton)findViewById(R.id.button_answer);
  btnAnswer.setOnClickListener(this);
  btnAnswerAudio=(ImageButton)findViewById(R.id.button_answer_audio);
  btnAnswerAudio.setOnClickListener(this);
  btnMuteAudio=(ImageButton)findViewById(R.id.button_mute_audio);
  btnMuteAudio.setOnClickListener(this);
  btnMuteVideo=(ImageButton)findViewById(R.id.button_mute_video);
  btnMuteVideo.setOnClickListener(this);
  btnKeypad=(ImageButton)findViewById(R.id.button_keypad);
  btnKeypad.setOnClickListener(this);
  lblCall=(TextView)findViewById(R.id.label_call);
  lblStatus=(TextView)findViewById(R.id.label_status);
  lblTimer=(TextView)findViewById(R.id.label_timer);
  alertDialog=new AlertDialog.Builder(CallActivity.this).create();
  device=RCClient.listDevices().get(0);
  PreferenceManager.setDefaultValues(this,"String_Node_Str",MODE_PRIVATE,R.xml.preferences,false);
  prefs=PreferenceManager.getDefaultSharedPreferences(this);
  final Intent intent=getIntent();
  if (intent.getAction() == RCDevice.OUTGOING_CALL) {
    btnAnswer.setVisibility(View.INVISIBLE);
    btnAnswerAudio.setVisibility(View.INVISIBLE);
  }
 else {
    btnAnswer.setVisibility(View.VISIBLE);
    btnAnswerAudio.setVisibility(View.VISIBLE);
  }
  keypadFragment=new KeypadFragment();
  isVideo=intent.getBooleanExtra(RCDevice.EXTRA_VIDEO_ENABLED,false);
  lblTimer.setVisibility(View.INVISIBLE);
  btnMuteAudio.setVisibility(View.INVISIBLE);
  btnMuteVideo.setVisibility(View.INVISIBLE);
  btnKeypad.setVisibility(View.INVISIBLE);
  FragmentTransaction ft=getFragmentManager().beginTransaction();
  ft.add(R.id.keypad_fragment_container,keypadFragment);
  ft.hide(keypadFragment);
  ft.commit();
  handleCall(intent);
}

Fixed version (ground truth):
@Override protected void onCreate(Bundle savedInstanceState){
  super.onCreate(savedInstanceState);
  requestWindowFeature(Window.FEATURE_NO_TITLE);
  getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD| WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED| WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
  getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_FULLSCREEN | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
  setContentView(R.layout.activity_call);
  btnHangup=(ImageButton)findViewById(R.id.button_hangup);
  btnHangup.setOnClickListener(this);
  btnAnswer=(ImageButton)findViewById(R.id.button_answer);
  btnAnswer.setOnClickListener(this);
  btnAnswerAudio=(ImageButton)findViewById(R.id.button_answer_audio);
  btnAnswerAudio.setOnClickListener(this);
  btnMuteAudio=(ImageButton)findViewById(R.id.button_mute_audio);
  btnMuteAudio.setOnClickListener(this);
  btnMuteVideo=(ImageButton)findViewById(R.id.button_mute_video);
  btnMuteVideo.setOnClickListener(this);
  btnKeypad=(ImageButton)findViewById(R.id.button_keypad);
  btnKeypad.setOnClickListener(this);
  lblCall=(TextView)findViewById(R.id.label_call);
  lblStatus=(TextView)findViewById(R.id.label_status);
  lblTimer=(TextView)findViewById(R.id.label_timer);
  alertDialog=new AlertDialog.Builder(CallActivity.this).create();
  device=RCClient.listDevices().get(0);
  PreferenceManager.setDefaultValues(this,"String_Node_Str",MODE_PRIVATE,R.xml.preferences,false);
  prefs=PreferenceManager.getDefaultSharedPreferences(this);
  final Intent intent=getIntent();
  if (intent.getAction().equals(RCDevice.OUTGOING_CALL)) {
    btnAnswer.setVisibility(View.INVISIBLE);
    btnAnswerAudio.setVisibility(View.INVISIBLE);
  }
 else {
    btnAnswer.setVisibility(View.VISIBLE);
    btnAnswerAudio.setVisibility(View.VISIBLE);
  }
  keypadFragment=new KeypadFragment();
  isVideo=intent.getBooleanExtra(RCDevice.EXTRA_VIDEO_ENABLED,false);
  lblTimer.setVisibility(View.INVISIBLE);
  btnMuteAudio.setVisibility(View.INVISIBLE);
  btnMuteVideo.setVisibility(View.INVISIBLE);
  btnKeypad.setVisibility(View.INVISIBLE);
  activityVisible=true;
  FragmentTransaction ft=getFragmentManager().beginTransaction();
  ft.add(R.id.keypad_fragment_container,keypadFragment);
  ft.hide(keypadFragment);
  ft.commit();
  handleCall(intent);
}