Something

//in choose-desktop.h
class ChooseDesktop : public Gtk::Dialog
{
public:

    ChooseDesktop()
        { doSetup(); }

    virtual ~ChooseDesktop()
        {}

private:

    void okCallback();
    void cancelCallback();

    bool doSetup();

    Gtk::Table table;

    Gtk::Label jidLabel;
    Gtk::Entry jidField;

    Gtk::Entry fileNameField;

    Gtk::Button selectFileButton;

};

// in session manager.cpp
    ChooseDesktop dialog();
    int result = dialog.run();
    dialog.hide();

// bash
error: request for member ‘run’ in ‘dialog’, which is of non-class type ‘ChooseDesktop ()()’