Add "See Migration Guide" button to the Project Manager

[patwork]

Adds a “See Migration Guide” button to the project update warning window. When clicked, a documentation page opens in an external browser:

https://docs.godotengine.org/en/stable/tutorials/migrating/

upgrade from 4.x:

upgrade from 3.x:

[Mickeon]

I think the feature is fine as is, but I wonder if it'd be doable to send the user to a more specific, appropriate page if the difference is one minor or major release (such as "4.4 -> 4.5"), and if the page is available, of course.

[KoBeWi]

The feature is fine, but the main problem is that it introduces a real maintenance burden. Right now the button opens Godot 4.5 migration guide, and greets the user with page not found. That's not acceptable, and it means we need to make sure we have a migration guide ready at least for the stable release, for each version onward, even if the guide is going to be empty.

I also wonder about the placement of the button. Wouldn't it be better if it was in the middle?

I wonder if it'd be doable to send the user to a more specific, appropriate page if the difference is one minor or major release

It would be best if we had a dedicated migration guide page that could generate its content dynamically. So you could open the page with current version and target version in the URL and it would copy-paste relevant guides between these versions. That's an overkill solution though. For now we could link previous and next migration guide in each page, so the user can quickly find them.

[patwork]

Fair points.

I agree that the need to update the documentation beforehand to make the button work properly is an unnecessary burden. That's why I changed the link to a universal address describing the procedure for migration to the new versions.

https://docs.godotengine.org/en/latest/tutorials/migrating/index.html

As recommended, I use GODOT_VERSION_DOCS_URL but I agree that it doesn't make sense to create a file-scope #define, because the url is only used in one place in one small function.

void ProjectManager::_migration_guide_button_pressed() {
	const String url = vformat("%s/tutorials/migrating/index.html", GODOT_VERSION_DOCS_URL);
	OS::get_singleton()->shell_open(url);
}

As for the placement of the button, I'm using AcceptDialog::add_button, which only allows adding a button "to the right" or "to the left." I suppose it would require directly accessing the buttons_hbox member of the AcceptDialog class to insert the button between Cancel and OK.

[akien-mga]

Thanks!