chat panel ++ (#4044)

- Update chat panel with current channel
- Open chat panel for guests
- Open chat when joining a channel with guests
- Some tweaks for chat panels
- Don't lose focus on default panel state
- Make chat prettier (to my eyes at least)
- Fix multiple mentions in one message
- Show a border when scrolled in chat
- Fix re-docking chat panel
- Move settings subscription to dock

[[PR Description]]

Release Notes:

- Opens chat by default when joining a public channel
- Improves chat panel UI

crates/gpui/src/elements/list.rs

@@ -43,6 +43,7 @@ pub enum ListAlignment {
 pub struct ListScrollEvent {
     pub visible_range: Range<usize>,
     pub count: usize,
+    pub is_scrolled: bool,
 }
 
 #[derive(Clone)]
@@ -253,6 +254,7 @@ impl StateInner {
                 &ListScrollEvent {
                     visible_range,
                     count: self.items.summary().count,
+                    is_scrolled: self.logical_scroll_top.is_some(),
                 },
                 cx,
             );

crates/gpui/src/styled.rs

@@ -1,7 +1,7 @@
 use crate::{
     self as gpui, hsla, point, px, relative, rems, AbsoluteLength, AlignItems, CursorStyle,
-    DefiniteLength, Display, Fill, FlexDirection, Hsla, JustifyContent, Length, Position,
-    SharedString, StyleRefinement, Visibility, WhiteSpace,
+    DefiniteLength, Display, Fill, FlexDirection, FontWeight, Hsla, JustifyContent, Length,
+    Position, SharedString, StyleRefinement, Visibility, WhiteSpace,
 };
 use crate::{BoxShadow, TextStyleRefinement};
 use smallvec::{smallvec, SmallVec};
@@ -494,6 +494,13 @@ pub trait Styled: Sized {
         self
     }
 
+    fn font_weight(mut self, weight: FontWeight) -> Self {
+        self.text_style()
+            .get_or_insert_with(Default::default)
+            .font_weight = Some(weight);
+        self
+    }
+
     fn text_bg(mut self, bg: impl Into<Hsla>) -> Self {
         self.text_style()
             .get_or_insert_with(Default::default)