Top of reaction picker can fall off the top of the screen

[dbkr]

Description

With messages a certain distance from the top, the top of the reaction picker can be off the top of the screen. Looks like the reaction picker is taller than it's expecting it to be?

Version information

• Platform: web (in-browser) or desktop?

For the web app:

desktop nightly

[SimonBrandner]

Related: #17527

[robintown]

(To repro, your window has to be vertically short)