Submenu alignment changed since 0.31.1

[torokati44]

Describe the bug

If a submenu doesn't fit in the viewport, now the middle of it is visible, not the top.

Is there a way to affect this somehow?

See the code that does this here: https://github.com/ruffle-rs/ruffle/blob/3ada4296b2bd839f04d0c1dbee79caccb902bc7b/desktop/src/gui/menu_bar.rs#L242-L282

To Reproduce
Steps to reproduce the behavior:

1. Make a menu bar
2. Add a menu button to it
3. Add a submenu to one of the items
4. Add an item with reeeeeeeeeeaaaaaalllyy long text to this submenu

Expected behavior

The submenu is still usable even if it's too tall (should be scrollable maybe?).

Screenshots

See: ruffle-rs/ruffle#20494 (comment)

Additional context

As also said in the linked issue comment, it might be up to us to trim/elide these long texts.
The cause might have been #5716, dunno...