gtkmm applications consist of windows containing widgets, such as buttons and text boxes. In some other systems, widgets are called "controls". For each widget in your application's windows, there is a C++ object in your application's code. So you just need to call a method of the widget's class to affect the visible widget.
Widgets are arranged inside container widgets such as frames and notebooks, in a hierarchy of widgets within widgets. Some of these container widgets, such as Gtk::VBox, are not visible - they exist only to arrange other widgets. Here is some example code that adds 2 Gtk::Button widgets to a Gtk::VBox container widgets:
m_box.pack_start(m_Button1); m_box.pack_start(m_Button2);and here is how to add the Gtk::VBox, containing those buttons, to a Gtk::Frame, which has a visible frame and title:
m_frame.add(m_box);
Most of the chapters in this book deal with specific widgets. See the Container Widgets section for more details about adding widgets to container widgets.