fltk-webview

This provides webview functionality for embedded fltk windows. This currently works on Windows:

Usage

```rust extern crate fltk;

use fltk::{app, enums::Event, prelude::*, window};

fn main() { let app = app::App::default(); let mut win = window::Window::default() .withsize(800, 600) .withlabel("Webview"); let mut wvwin = window::Window::default() .withsize(790, 590) .centerof_parent(); win.end(); win.show();

// close the app when the main window is closed
win.set_callback(|_| {
    if app::event() == Event::Close {
        std::process::exit(0);
    }
});

let mut wv = fltk_webview::Webview::create(false, &mut wv_win);
wv.navigate("http://wikipedia.com");

// the webview handles the main loop
wv.run();

} ```

Limitations

On windows, webview requires winrt headers, that means it's basically buildable with the MSVC toolchain. For Msys2/mingw, there are efforts to provide such headers, but nothing yet upstream.
On macos, unhandled objective-c exceptions can lead to faulty behavior.
On linux, I can't construct a GtkWindow from an FLTK window nor from an FLTK raw handle (xid). If you're able to do so, your help is needed!

alt_test