Hi, in Qt, wx, gtk and many others, you can embed a window inside them, (draw the window inside your application), for example you can embed mpv or mplayer inside your window and make a video player, you can embed a web-browser like chromedriver(something like that) and have a browser inside your app, is it possible to do it in godot? today godot doesn't support mp4 format and many other formats, I just wanted to embed a powerful, mature video player inside my app, is it possible? thank you!

Keep in mind that if it’s a proprietary file formate, there’s a 99% chance that Godot doesn’t support it. Probably want to convert mp4 to webm or ogv. There seems to be a video player node in Godot, did that not work? It’s probably just mostly used for playing cutscenes. If you want all the player buttons and functionality you’ll have to roll up your sleeves and implement them yourself. Here’s one older vid on it:

The documentation looks like the node itself is still pretty primitive: https://docs.godotengine.org/en/stable/classes/class_videoplayer.html

Godot doesn't support embedding other windows inside (and other applications can't embed Godot yet, except on Android).

There are no plans to implement support for this in the near future (before 4.0, that is). If this is ever implemented, this will be in a 4.x release which is a long time away.