Don't focus editor when clicking on sidebar resize handle

crates/workspace/src/sidebar.rs

@@ -165,6 +165,7 @@ impl Sidebar {
             ..Default::default()
         })
         .with_cursor_style(CursorStyle::ResizeLeftRight)
+        .on_mouse_down(|_, _| {}) // This prevents the mouse down event from being propagated elsewhere
         .on_drag(move |delta, cx| {
             let prev_width = *actual_width.borrow();
             *custom_width.borrow_mut() = 0f32