OpenEuphoria

I hesitate to say 'never', but you're never going to get this to work reliably. First of all, the reason the file dialog doesn't respond to button clicks, closing, etc, is because you never enter the GTK main processing loop, which is what watches for events.

You do this with main()

And once you enter the main processing loop, you'll be interfering with ed's own main loop, which likewise watches for events (mostly key presses). GTK will catch the keypresses, etc. first.

There may be a way to pass events through GTK back to ed, but it would be tricky. Kinda like putting Republicans and Democrats in the same room and expecting something good to come out of it...