Demonstrate one way to integrate SFML, SFGUI and OSG. It's a problem of input from the user. It would be good if they checked whether the widget is focused SFGUI and if so, the incident would not bubble through to the OSG. If anyone know how to implement it by writing in the comments.

main.cpp

/* OpenSceneGraph example, osgviewerSFML.
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to deal
 *  in the Software without restriction, including without limitation the rights
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *  copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *  THE SOFTWARE.
 */

/**
* Updated by Denis Colesnicov <eugustus@gmail.com>
*/

#include <memory>
#include <iostream>
#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>
#include <osgGA/TrackballManipulator>
#include <osgDB/ReadFile>
#include <SFML/Window.hpp>

#include <SFGUI/SFGUI.hpp>
#include <SFGUI/Widgets.hpp>

template<typename G,typename W>
bool convertEvent(sf::Event& event, G gw, W window)
{
    auto eventQueue = gw->getEventQueue();

    switch (event.type)
    {
    case sf::Event::MouseMoved:
        eventQueue->mouseMotion(event.mouseMove.x, event.mouseMove.y);
        return true;

    case sf::Event::MouseButtonPressed:
        if( event.mouseButton.button == sf::Mouse::Left )
        {
            event.mouseButton.button = static_cast<decltype(event.mouseButton.button)>(1);
        }
        else if( event.mouseButton.button == sf::Mouse::Right )
        {
            event.mouseButton.button = static_cast<decltype(event.mouseButton.button)>(3);
        }
        eventQueue->mouseButtonPress(event.mouseButton.x, event.mouseButton.y, event.mouseButton.button);
        return true;

    case sf::Event::MouseButtonReleased:
        if( event.mouseButton.button == sf::Mouse::Left )
        {
            event.mouseButton.button = static_cast<decltype(event.mouseButton.button)>(1);
        }
        else if( event.mouseButton.button == sf::Mouse::Right )
        {
            event.mouseButton.button = static_cast<decltype(event.mouseButton.button)>(3);
        }
        eventQueue->mouseButtonRelease(event.mouseButton.x, event.mouseButton.y, event.mouseButton.button);
        return true;

    case sf::Event::KeyReleased:
        eventQueue->keyRelease( (osgGA::GUIEventAdapter::KeySymbol) event.key.code);
        return true;

    case sf::Event::KeyPressed:
        eventQueue->keyPress( (osgGA::GUIEventAdapter::KeySymbol) event.key.code);
        if ( event.key.code == sf::Keyboard::Escape )
        {
            window->close();
        }
        return true;

    case sf::Event::Resized:
        eventQueue->windowResize(0, 0, event.size.width, event.size.height );
        gw->resized(0, 0, event.size.width, event.size.height );
        return true;

    case sf::Event::Closed:
        window->close();
        return true;

    default:
        break;
    }

    return false;
}

static std::shared_ptr<sf::Window> CreateWindowS( std::string title, unsigned int width, unsigned int height )
{
    return std::make_shared<sf::Window>(
               sf::VideoMode(width, height),
               sf::String::fromUtf8(title.begin(),title.end()),
               sf::Style::Default,
               sf::ContextSettings(24) );
}

int main( int argc, char **argv )
{

    // load the scene.
    auto   loadedModel = osgDB::readRefNodeFile("cow.osg");

    if (!loadedModel)
    {
        std::cout << "cow.osg: No data loaded." << std::endl;
        return EXIT_FAILURE;
    }

    int width = 800;
    int height = 600;

    auto  window = CreateWindowS("OSG Viewer",width,height);

    osgViewer::Viewer    viewer;

    auto gw = viewer.setUpViewerAsEmbeddedInWindow(0,0,width,height);

    viewer.setSceneData(loadedModel.get());
    viewer.setCameraManipulator(new osgGA::TrackballManipulator);
    viewer.addEventHandler(new osgViewer::StatsHandler);
    viewer.realize();

    // Create an SFGUI. This is required before doing anything with SFGUI.
    sfg::SFGUI sfgui;

    sfg::Entry::Ptr g_textarea = sfg::Entry::Create();
    g_textarea->SetRequisition( sf::Vector2f( 100.f, .0f ) );

    auto g_window = sfg::Window::Create();
    g_window->SetTitle( "SFGUI with OpenGL" );

    sfg::Desktop desktop;
    g_window->Add(g_textarea);

    desktop.Add( g_window );


    while( window->isOpen() )
    {
        sf::Event   event;

        while ( window->pollEvent(event) )
        {
            desktop.HandleEvent( event );
            // pass the SFML event into the viewers event queue
            convertEvent( event, gw, window );
        }

        viewer.frame();

        // SFGUI rendering.
        desktop.Update( 0.0f );

        sfgui.Display( *(window.get() ));
        window->display();
    }

    return EXIT_SUCCESS;
}

Known problems:

• problems with focus sfgu windows/controls