This is part of a more general work dedicated to gtkmm accessible here. This example shows how to create a Gtk::Scale widget:

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Source code

main.cpp

#include 
#include 


int main(int argc, char* argv[])
{
	// Initialize gtkmm
	Gtk::Main app(argc, argv);
	// Create the window
	mainwindow w;
	// Start main loop
	Gtk::Main::run(w);
	return 0;
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include 


// The class mainwindow inherits from Gtk::Window
class mainwindow : public Gtk::Window
{
	// Constructor and destructor
public:    
	mainwindow();
	virtual             ~mainwindow();

protected:
	//Signal handlers (run when the button are clicked)
	void                  on_button();
	void                  on_scale_change();

	//Member widgets:
	Gtk::Button           button1;
	Gtk::Scale            scale;
	Gtk::Button           buttonQuit;
	Gtk::Grid             mainGrid;
};


#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include 
#include 


// Constructor of the main Window (build ui interface).
mainwindow::mainwindow()
{
	// Initialize the main window
	this->set_title("Scroll bar");
	this->set_border_width(10);

	// Create the first button
	button1.add_label("Display value");
	button1.set_size_request(150,50);
	button1.signal_clicked().connect(sigc::mem_fun(*this,&mainwindow::on_button));
	mainGrid.attach(button1,0,0,1,1);

	// Add the Quit button
	buttonQuit.add_label("Quit");
	buttonQuit.set_size_request(150,50);
	buttonQuit.signal_clicked().connect(sigc::mem_fun(*this,&mainwindow::close));
	mainGrid.attach(buttonQuit,1,0,1,1);

	// Add the scroll bar
	scale.set_range(0,100);
	scale.set_value(50);
	scale.signal_value_changed().connect(sigc::mem_fun(*this,&mainwindow::on_scale_change));
	mainGrid.attach(scale,0,1,2,1);

	// Display the main grid in the main window
	mainGrid.show_all();
	add(mainGrid);
}


// Destructor of the class
mainwindow::~mainwindow()
{}


// Call when the button is clicked
void mainwindow::on_button()
{
	std::cout << "Current value is: " << scale.get_value() << std::endl;
}


// Call when the scroll bar value is changed
void mainwindow::on_scale_change()
{
	std::cout << "Value updated" << std::endl;
}