Simple say window show/hide transforms

[kigyo]

What I'm looking for is to apply a transform to the say window once when it appears on-screen, and once when it's hidden. This would be far more restrictive than the way show and hide currently work with the say screen.

Ideally, when using the transform below, the behavior would be that the text window slides out when a transition occurs, or a screen is called, etc. It then slides back in when the dialogue continues. Between two lines of dialogue, nothing should happen.

transform say_window_animation:
    on show:
        yoffset 330 alpha 0
        linear 0.3 yoffset 0 alpha 1.0
    on hide:
        yoffset 0 alpha 1
        linear 0.3 yoffset 330 alpha 0

(As a side note, I was also thinking about an event / transform whenever the speaking character changes, but I want to keep this request as simple as possible for now.)

One thing that would already help is that all pauses inside a say statement should be considered replaces, including the first one. (Thereby removing i != 0 and from line 677 in character.py.)

Is there a way to achieve this effect? Or could this be a feature that will be added in the future?

[mal]

This seems to sound like config.window_hide_transition and config.window_show_transition.
https://www.renpy.org/doc/html/config.html#var-config.window_hide_transition