Keyboard can obscure compose box in landscape

[gnprice]

Repro:

1. Open the compose box, in landscape orientation.
2. Type several lines of text, so that there isn't room to show the whole draft message.
3. First, the compose box grows to obscure the message list, as expected. Then when there's no more room for that:
4. Expected: The compose text input becomes scrollable, to move through the draft message.
5. Actual: The compose box keeps growing. The compose buttons get pushed down so the keyboard obscures them; then the text input itself extends down to where the keyboard obscures the bottom of the text input, too.

Reported originally in the Rust community, on Android. Here's a screen recording:
https://github.com/user-attachments/assets/aade2e95-e6a1-4f94-9946-8c2c917bb8b0

I also reproduce, on my Pixel 8 running Android 15.

References

• Chat thread: #mobile > landscape mode keyboard issue
• Original report in Rust community

[gnprice]

Copying here a speculation I made on the chat thread (#mobile > landscape mode keyboard issue @ 💬) about possible causes:

Here's the left side of the screen at one key moment in that video:

One thing I notice there is that the compose box can be seen extending off to the left of the keyboard — the keyboard doesn't extend all the way to the far left of the screen.

I suspect that one thing happening here might be that because the keyboard doesn't extend all the way to the left and right edges, the value we get for the bottom inset — the width of a band on the bottom of the screen where the system's UI is in the way so we can't count on using the space normally — might not take the keyboard into account.

[gnprice]

Just reproduced on iOS too, so this doesn't appear to have any interaction with Android vs. iOS.