Mobile: Last torrent in list blocked by menubar

[Asinin3]

Description

When scrolling down your list of torrents the menubar always appears (it goes away if scrolling up). However, if you scroll really fast to get to the bottom the menubar stays hidden.

Screen recording:
https://github.com/user-attachments/assets/d28a5163-28d3-4156-bf4f-0f93d4a5494e

In a scenario where you have 100 torrents, and you are scrolled 80 down, you can quickly scroll to the bottom and there's no issue as the menubar doesn't appear and you can click on the last one. However if you were scrolled to e.g 95/100 then scroll to the last one the menubar will keep appearing and disappearing over the top of the last torrent making it impossible to select.

Steps to reproduce

No response

Environment

qui: 1.26
Firefox Mobile (PWA App) 153

Relevant logs

No response

Checklist

• I have searched existing discussions and issues
• I have checked the documentation

[MLuc24]

The reason it behaves differently depending on how fast you scroll is that the visibility logic only looks at direction, never at position. From MobileScrollContext.tsx:

const threshold = 10

if (Math.abs(scrollY - lastScrollY.current) < threshold) {
  ticking.current = false
  return
}

if (scrollY > lastScrollY.current) {
  setIsFooterVisible(false) // Hide on scroll down
} else {
  setIsFooterVisible(true) // Show on scroll up
}

There's no reference to scrollHeight or clientHeight anywhere in it, so the context has no idea whether you're in the middle of the list or at the end. Any movement upward larger than 10px means "show", full stop.

That's what produces your flicker. When you arrive at the bottom gently, the container rubber-bands as it settles — scrollTop dips back a little, which reads as an upward scroll and shows the bar, then settles forward again and hides it. Repeat while it oscillates and the bar strobes over the last row. Arriving on a fast fling gets you there in one continuous downward run with no settle, which is why the bar stays hidden and the last torrent is clickable — exactly the asymmetry you described.

The fix is to give it a notion of "at the bottom", since once you're there the bar has nothing left to uncover:

const atBottom = scrollContainer.scrollTop + scrollContainer.clientHeight
  >= scrollContainer.scrollHeight - threshold

if (atBottom) {
  setIsFooterVisible(false)
} else if (scrollY > lastScrollY.current) {
  ...

That also fixes it for anyone whose device does more aggressive overscroll than yours, which is probably why this hasn't been reported more often — the bounce distance varies a lot between browsers and platforms, and on some it never crosses the 10px threshold at all.