[Windows] Implement native file selection dialog support.

[bruvzg]

Follow up to #47499

Implements DisplayServer.file_dialog_show() for Windows.

• Production edit: This partially addresses Allow use of native system file picker dialog on iOS and web godot-proposals#1123.

[YuriSizov]

The passthrough option from the FileDialog seems to work correctly. But when calling DisplayServer.file_dialog_show(), I can't seem to change the current directory with any of these:

DisplayServer.file_dialog_show("Hello!", ".", "", false, DisplayServer.FILE_DIALOG_MODE_OPEN_ANY, [], _callback)
DisplayServer.file_dialog_show("Hello!", "res://", "", false, DisplayServer.FILE_DIALOG_MODE_OPEN_ANY, [], _callback)
DisplayServer.file_dialog_show("Hello!", ProjectSettings.globalize_path("res://"), "", false, DisplayServer.FILE_DIALOG_MODE_OPEN_ANY, [], _callback)
DisplayServer.file_dialog_show("Hello!", "C:/", "", false, DisplayServer.FILE_DIALOG_MODE_OPEN_ANY, [], _callback)
DisplayServer.file_dialog_show("Hello!", "C:\\", "", false, DisplayServer.FILE_DIALOG_MODE_OPEN_ANY, [], _callback)

It always opens the user directory instead. Windows 11 by the way.

[KoBeWi]

Tested on Windows 10, I also can't change current directory.
Although it does not always open in user. It opens the last directory I picked something from. I observed such behavior in various apps (most notably in Chrome), so it's at least consistent with how native file dialogs usually work on Windows.

EDIT:
btw when native file dialog is opened, the Godot window becomes unresponsive.

[bruvzg]

Setting directory should be fixes.

[YuriSizov]

Thanks!

[KoBeWi]

And what about the unresponsive background window? 🙃

[YuriSizov]

I think that might be by design? Isn't it always blocking the main window when a native app brings that dialog? But feel free to open the issue.

[bruvzg]

And what about the unresponsive background window? 🙃

Have not seen the edit, the function is blocking, and I am not sure if there's a way to plug in redraw into its modal event loop. But I dialog can be shown from a thread, I'll take a look if it can be improved.

[KoBeWi]

I checked how Chrome handles it. When you click outside the dialog, the dialog will briefly blink and play the Background sound.

EDIT:
Opened an issue: #79642