Resizable_rubber_band http://stackoverflow.com/questions/19066804/implementing-resize-handles-on-qrubberband-is-qsizegrip-relevant/19067132

main.cpp

#include "MainWindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
  QApplication a(argc, argv);
  MainWindow w;
  w.show();


  return a.exec();
}

MainWindow.cpp

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QDebug>
#include <QFile>
#include <QRubberBand>
#include <QSizeGrip>

MainWindow::MainWindow(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::MainWindow)
{
  ui->setupUi(this);
  Resizable_rubber_band* band = new Resizable_rubber_band(ui->label);
  band->move(100, 100);
  band->resize(50, 50);
  band->setMinimumSize(30, 30);
  //band->show();
  //QSizeGrip* g = new QSizeGrip(band);

}

MainWindow::~MainWindow()
{
  delete ui;
}


Resizable_rubber_band::Resizable_rubber_band(QWidget *parent) : QWidget(parent) {
  //tell QSizeGrip to resize this widget instead of top-level window
  setWindowFlags(Qt::SubWindow);
  QHBoxLayout* layout = new QHBoxLayout(this);
  layout->setContentsMargins(0, 0, 0, 0);
  QSizeGrip* grip1 = new QSizeGrip(this);
  QSizeGrip* grip2 = new QSizeGrip(this);
  layout->addWidget(grip1, 0, Qt::AlignLeft | Qt::AlignTop);
  layout->addWidget(grip2, 0, Qt::AlignRight | Qt::AlignBottom);
  rubberband = new QRubberBand(QRubberBand::Rectangle, this);
  rubberband->move(0, 0);
  rubberband->show();
}

void Resizable_rubber_band::resizeEvent(QResizeEvent *) {
  rubberband->resize(size());
}

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTcpServer>
#include <QDialog>
#include <QRubberBand>

namespace Ui {
class MainWindow;
}


class Resizable_rubber_band : public QWidget {
public:
  Resizable_rubber_band(QWidget* parent = 0);

private:
  QRubberBand* rubberband;
  void resizeEvent(QResizeEvent *);

};


class QConsole : public QDialog

{
  Q_OBJECT
public:
  void init() {
    qDebug() << m_Server.listen(QHostAddress::Any, 12346);
    QDialog::connect(&m_Server, SIGNAL(newConnection()), this, SLOT(new_Connection()));

  }

public slots:
  void new_Connection() {
    qDebug() << "OK! new_Connection";
  }

private:
  QTcpServer m_Server;
};



class MainWindow : public QMainWindow
{
  Q_OBJECT
  
public:
  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();
  
private:
  Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

MainWindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>526</width>
    <height>392</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralWidget">
   <layout class="QGridLayout" name="gridLayout">
    <item row="0" column="0">
     <widget class="QLabel" name="label">
      <property name="text">
       <string/>
      </property>
      <property name="pixmap">
       <pixmap>c:/Users/Ri/Pictures/ava.jpg</pixmap>
      </property>
      <property name="scaledContents">
       <bool>true</bool>
      </property>
     </widget>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menuBar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>526</width>
     <height>21</height>
    </rect>
   </property>
  </widget>
  <widget class="QToolBar" name="mainToolBar">
   <attribute name="toolBarArea">
    <enum>TopToolBarArea</enum>
   </attribute>
   <attribute name="toolBarBreak">
    <bool>false</bool>
   </attribute>
  </widget>
  <widget class="QStatusBar" name="statusBar"/>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>

untitled.pro

#-------------------------------------------------
#
# Project created by QtCreator 2013-09-26T13:32:37
#
#-------------------------------------------------

QT       += core gui network

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = untitled
TEMPLATE = app


SOURCES += main.cpp\
        MainWindow.cpp

HEADERS  += MainWindow.h

FORMS    += MainWindow.ui