Also, advanced features like ExternalInterface communication with the SWF, or internal plugin functions are also available (but lacks documentation).

If you want to use it, you need to open two anonymous pipe, and run (fork-exec) gnash with `--fd` parameter supplying the pipes' file descriptor number. Then you could communicate with the SWF inside Gnash. The exact protocol used here is not documented, you'll need to read libgnashcore's `movie_root.cpp` to find information about it.

Hope anyone stumbled on this thread find them useful.

This support thread is quite old, but since I have never found anyone writing example on how to do this, I'm going to document it here in case anyone need it.

As you probably know, Gnash is divided into few libraries (libgnashbase, libgnashcore, libgnashsound, libgnashmedia, libgnashdevice, and libgnashrender), and player applications (gtk-gnash, qt-gnash, sdl-gnash, fb-gnash, and dump-gnash).

But if you are going to just play SWF file, I'd personally advice against using Gnash's internal libraries directly (they are not documented, and prone to changes).

Instead, invoke Gnash as an external application, and instruct it to display output inside your program, using toolkit's XEmbed feature. (Gnash's Firefox plugin worked this way too).

To do so, your application must place an XEmbed widget on the screen, obtain X11 window ID from your widget, then start Gnash externally with `--xid` parameter supplying the window ID you just obtained. Once Gnash started, the SWF will display inside your application's widget, and user could interact with it the same way as you did in Gnash.

For Qt4 application (your case), the XEmbed container widget is QX11EmbedContainer class. To obtain X11 window ID of the widget, use `QWidget::winId()`

For GTK2 application, the XEmbed container widget is GtkSocket class.
To obtain X11 window ID of the widget, use `gtk_socket_get_id()`.

As you used Qt, it is better if you run `qt4-gnash` rather than `gtk-gnash` or plain `gnash`, as GTK Gnash has some resizing problem when embeded into Qt4 application.

When you are finished with the SWF-displaying screen, don't forget to kill Gnash process that you have launched too.