Checkpoint: Narrow down error

crates/gpui2/src/platform/mac/display_linker.rs

@@ -26,13 +26,13 @@ impl MacDisplayLinker {
     }
 }
 
-type OutputCallback = Mutex<Box<dyn FnMut(&VideoTimestamp, &VideoTimestamp)>>;
+type OutputCallback = Mutex<Box<dyn FnMut(&VideoTimestamp, &VideoTimestamp) + Send>>;
 
 impl MacDisplayLinker {
     pub fn set_output_callback(
         &mut self,
         display_id: DisplayId,
-        output_callback: Box<dyn FnMut(&VideoTimestamp, &VideoTimestamp)>,
+        output_callback: Box<dyn FnMut(&VideoTimestamp, &VideoTimestamp) + Send>,
     ) {
         if let Some(mut system_link) = unsafe { sys::DisplayLink::on_display(display_id.0) } {
             let callback = Arc::new(Mutex::new(output_callback));

crates/gpui2/src/platform/mac/platform.rs

@@ -494,7 +494,7 @@ impl Platform for MacPlatform {
     fn set_display_link_output_callback(
         &self,
         display_id: DisplayId,
-        callback: Box<dyn FnMut(&VideoTimestamp, &VideoTimestamp)>,
+        callback: Box<dyn FnMut(&VideoTimestamp, &VideoTimestamp) + Send>,
     ) {
         self.0
             .lock()

crates/gpui2/src/platform/test/platform.rs

@@ -81,7 +81,7 @@ impl Platform for TestPlatform {
     fn set_display_link_output_callback(
         &self,
         _display_id: DisplayId,
-        _callback: Box<dyn FnMut(&crate::VideoTimestamp, &crate::VideoTimestamp)>,
+        _callback: Box<dyn FnMut(&crate::VideoTimestamp, &crate::VideoTimestamp) + Send>,
     ) {
         unimplemented!()
     }