linux: Primary clipboard (#10534)

Implements copying from and pasting to the primary selection.

Release Notes:

- N/A

crates/terminal/src/terminal.rs

@@ -750,6 +750,11 @@ impl Terminal {
             InternalEvent::SetSelection(selection) => {
                 term.selection = selection.as_ref().map(|(sel, _)| sel.clone());
 
+                #[cfg(target_os = "linux")]
+                if let Some(selection_text) = term.selection_to_string() {
+                    cx.write_to_primary(ClipboardItem::new(selection_text));
+                }
+
                 if let Some((_, head)) = selection {
                     self.selection_head = Some(*head);
                 }
@@ -766,6 +771,11 @@ impl Terminal {
                     selection.update(point, side);
                     term.selection = Some(selection);
 
+                    #[cfg(target_os = "linux")]
+                    if let Some(selection_text) = term.selection_to_string() {
+                        cx.write_to_primary(ClipboardItem::new(selection_text));
+                    }
+
                     self.selection_head = Some(point);
                     cx.emit(Event::SelectionsChanged)
                 }
@@ -1192,7 +1202,12 @@ impl Terminal {
         Some(scroll_delta)
     }
 
-    pub fn mouse_down(&mut self, e: &MouseDownEvent, origin: Point<Pixels>) {
+    pub fn mouse_down(
+        &mut self,
+        e: &MouseDownEvent,
+        origin: Point<Pixels>,
+        cx: &mut ModelContext<Self>,
+    ) {
         let position = e.position - origin;
         let point = grid_point(
             position,
@@ -1229,6 +1244,11 @@ impl Terminal {
                 self.events
                     .push_back(InternalEvent::SetSelection(Some((sel, point))));
             }
+        } else if e.button == MouseButton::Middle {
+            if let Some(item) = cx.read_from_primary() {
+                let text = item.text().to_string();
+                self.input(text);
+            }
         }
     }