Fl_Window subclass doesn't work - c++

Question

As titled above, i'm trying to get an extremely simple FLTK 1.3.3 application working.
But, even with only a simple Fl_Window and 1 Fl_Button, nothing seems to work. Can anyone help?
class MainEditorWindow : public Fl_Window
{
public:
MainEditorWindow(int _width, int _height, std::string _title);
~MainEditorWindow();
virtual void draw();
virtual int handle(int _event);
private:
Fl_Button* m_btnExit;
};
And here is the Implementation
MainEditorWindow::~MainEditorWindow()
{
}
int MainEditorWindow::handle(int _event)
{
return 1;
}
void MainEditorWindow::draw()
{
m_btnExit->redraw();
}
MainEditorWindow::MainEditorWindow(int _width, int _height, std::string _title) : Fl_Window(_width, _height, _title.c_str())
{
this->begin();
m_btnExit = new Fl_Button(0, 0, 40, 40, "EXIT");
m_btnExit->color(FL_RED);
this->color(FL_WHITE);
this->end();
}
But when simply running the application like this:
int main(int argc, char** argv)
{
MainEditorWindow* mw = new MainEditorWindow(800, 600, "SHIP Editor");
mw->show(argc,argv);
return Fl::run();
}
The window shows up fine, its resizable movable etc, the draw() - function is being called and all that. But the window itself is just blank. It simply shows nothing, especially not the Fl_Button. Can anybody tell me why this occurs? As far as i can tell, there should be nothing particularily wrong with my code.

Answer 1

You need to call Fl_Window::draw()
void MainEditorWindow::draw()
{
m_btnExit->redraw();
Fl_Window::draw();
}
And maybe you want the button is clickable too
int MainEditorWindow::handle(int _event)
{
//return 1;
return(Fl_Window::handle(_event));
}

Answer 2

Try this in your MainEditorWindow constructor:
MainEditorWindow(int _width, int _height, const std::string& _title)
: Fl_Window(_width, _height, _title.c_str()) {
// begin grouped GUI object creation
Fl_Group::begin();
// alter x,y coords of button as necessary
m_btnExit = new Fl_Button(0,0,40,40,"EXIT");
m_btnExit->color(FL_RED);
// end grouped GUI object creation
Fl_Group::end();
// defines resizable widget for group
Fl_Group::resizable(this);
this->color(FL_WHITE);
// display window
Fl_Window::show();
}
Then in main:
int main(int argc, char** argv) {
MainEditorWindow mw(800, 600, "SHIP Editor");
return Fl::run();
}
Here we have added the button to a group and then invoked Fl_Window::show() inside the constructor to display it.
Note there is no need to make mw a pointer to MainEditorWindow in main.