Composer goes off screen on iOS when starting to type

[matteocontrini]

Bug Report

Current Behavior

After #2279 and #2631 were applied, when replying to a discussion on iOS by tapping the "reply" area at the bottom of a discussion, it happens that when the user starts typing the composer goes off the screen, even if its position is fixed, and the user needs to scroll up.

Steps to Reproduce

1. Go to a forum on nightly with Safari on iOS
2. Open a discussion
3. Tap the "reply" area at the bottom
4. Tap the composer textbox and start writing
5. Sometimes: the page will scroll to the bottom and the composer will go off screen, forcing you to scroll up manually

Expected Behavior

The composer should be fixed at the top.

Screenshots

Environment

• Flarum version: beta.15 with changes from Fix composer header hidden by mobile browser #2279 and Fix keyboard on small mobile screens hiding composer #2631 applied
• Website URL: https://forum.fibra.click
• Browser: Safari on iOS. I don't have the versions.

I'll ask the iOS user reporting this to test on nightly.flarum.site to see if it might be an extension or something else on my forum causing this.

[matteocontrini]

Confirmed on nightly. It doesn't happen always but most of the times, also on iPad although it just bumps a bit.

IMG_1920.MP4

[SychO9]

Thank you!

Did some research, I now understand why the composer was initially using position: absolute, fixed position with the virtual keyboard just doesn't work on iOS.

https://medium.com/@im_rahul/safari-and-position-fixed-978122be5f29
https://gist.github.com/avesus/957889b4941239490c6c441adbe32398#:~:text=Mobile%20Safari%20does%20not%20support,%2C%20focus%20%2C%20and%20blur%20events.

I don't think we should revert back to absolute positioning though, as that fixed a couple of annoying issues. What we should do is only apply the old absolute positioning for iOS users.