content/msglist: Horizontal scrollbar in code block sometimes has wrong vertical position

[chrisbobbe]

In the code block in this screenshot, the scroll bar should be positioned lower than it is:

I think it might have to do with the bottom inset. I seem to be seeing it in the "Combined feed" but not any other message-list views. "Combined feed" behaves differently about padding the bottom inset because it doesn't show the compose box.

[chrisbobbe]

Looks like this broke in this commit:

6a8cf5c msglist [nfc]: Unpack to a CustomScrollView of a single sliver

From CustomScrollView's dartdoc:

/// [CustomScrollView]s don't automatically avoid obstructions from [MediaQuery]
/// like [ListView]s do. To reproduce the behavior, wrap the slivers in
/// [SliverSafeArea]s.

Here's before and after that commit (which was in January, so the appearance won't be current in either screenshot):

Before	After

[chrisbobbe]

We could fix it in main by wrapping our SliverStickyHeaderList sliver in a SliverSafeArea, when the narrow is "Combined feed". (And add a TODO(#311) like the ones we have already.)

@gnprice, would this approach disrupt your work toward #82?

Then for a regression test, maybe we render a CodeBlock in the message list on the "Combined feed" page, and check that it receives a MediaQuery.padding.bottom of zero.

[gnprice]

Hmm interesting, good catch.

Wrapping in a SliverSafeArea would mean that the actual list stays out of the bottom inset area, right? That doesn't seem like the desired behavior — I think it's expected that the messages scroll visibly through that bottom area.

A MediaQuery.removePadding might be a good fix. That would mean that the list forgets that there is a bottom inset.

[chrisbobbe]

Wrapping in a SliverSafeArea would mean that the actual list stays out of the bottom inset area, right? That doesn't seem like the desired behavior — I think it's expected that the messages scroll visibly through that bottom area.

Hmm, this isn't what I'm seeing: screenshots at PR #738.