Reintroduce LSP diagnostic/status message (#3728)

Release Notes:

- N/A

crates/workspace2/src/pane.rs

@@ -789,6 +789,7 @@ impl Pane {
             }
 
             self.update_toolbar(cx);
+            self.update_status_bar(cx);
 
             if focus_item {
                 self.focus_active_item(cx);
@@ -1450,6 +1451,22 @@ impl Pane {
         });
     }
 
+    fn update_status_bar(&mut self, cx: &mut ViewContext<Self>) {
+        let workspace = self.workspace.clone();
+        let pane = cx.view().clone();
+
+        cx.window_context().defer(move |cx| {
+            let Ok(status_bar) = workspace.update(cx, |workspace, _| workspace.status_bar.clone())
+            else {
+                return;
+            };
+
+            status_bar.update(cx, move |status_bar, cx| {
+                status_bar.set_active_pane(&pane, cx);
+            });
+        });
+    }
+
     fn render_tab(
         &self,
         ix: usize,

crates/workspace2/src/status_bar.rs

@@ -83,6 +83,9 @@ impl StatusBar {
     where
         T: 'static + StatusItemView,
     {
+        let active_pane_item = self.active_pane.read(cx).active_item();
+        item.set_active_pane_item(active_pane_item.as_deref(), cx);
+
         self.left_items.push(Box::new(item));
         cx.notify();
     }
@@ -119,6 +122,9 @@ impl StatusBar {
     ) where
         T: 'static + StatusItemView,
     {
+        let active_pane_item = self.active_pane.read(cx).active_item();
+        item.set_active_pane_item(active_pane_item.as_deref(), cx);
+
         if position < self.left_items.len() {
             self.left_items.insert(position + 1, Box::new(item))
         } else {
@@ -141,6 +147,9 @@ impl StatusBar {
     where
         T: 'static + StatusItemView,
     {
+        let active_pane_item = self.active_pane.read(cx).active_item();
+        item.set_active_pane_item(active_pane_item.as_deref(), cx);
+
         self.right_items.push(Box::new(item));
         cx.notify();
     }