How to hide ubuntu title bar while opening new window on top of main window

[guru007]

I am building an app in which application window should be always fullscreen.Main window is fullscreen with no problem.But when I open a new window inside constructor of main window it shows top bar of Ubuntu which contain battery,wifi information etc.
My Question is how to get rid of that title bar while popping up new QWidget.
Here is link to screenshot:
http://ibin.co/2S3nRGxEezwz
This is code snippet:
mpd.cpp // mainwindow class
#include "mpd.h"
#include "ui_mpd.h"
#include "header.h"
mpd::mpd(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::mpd)
{
ui->setupUi(this);
select_route = new route_selection;
select_route->setWindowFlags(Qt::Widget | Qt::FramelessWindowHint);
select_route->show();
}

mpd::~mpd()
{
delete ui;
}
route_selection::route_selection(QWidget *parent) :
QWidget(parent),
ui(new Ui::route_selection)
{
ui->setupUi(this);
train_selection_keyboard = new keyboard(this);
ui->stackedWidget->addWidget(train_selection_keyboard);
ui->stackedWidget->setCurrentWidget(train_selection_keyboard);
this->setGeometry(100,200,this->width(),this->height());
this->setWindowFlags(Qt::FramelessWindowHint);

[mrjj]

hi
if you give full screen as parent , does it still do this ?
select_route = new route_selection;
-->
select_route = new route_selection(this);

[guru007]

I changed
select_route = new route_selection(this);
but still showing same behaviour.

[mrjj]

@guru007
could you also try
route_selection->setWindowFlags(Qt::WindowStaysOnTopHint);
(for test)

[guru007]

Thanks @mrjj My problem is solved with setWindowFlags(Qt::WindowStaysOnTopHint);

[mrjj]

@guru007
ok super so that keeps ubuntu from re-showing the status bar.
Happy coding.