Windows: Better cursor (#9451)

Moved `SetCursor` calls to `WM_SETCURSOR`, which occurs when OS is
requires set cursor.

Release Notes:

- N/A

crates/gpui/src/platform/windows/platform.rs

@@ -62,6 +62,8 @@ pub(crate) struct WindowsPlatformInner {
     pub(crate) dispatch_event: OwnedHandle,
     pub(crate) settings: RefCell<WindowsPlatformSystemSettings>,
     pub icon: HICON,
+    // NOTE: standard cursor handles don't need to close.
+    pub(crate) current_cursor: Cell<HCURSOR>,
 }
 
 impl WindowsPlatformInner {
@@ -157,6 +159,7 @@ impl WindowsPlatform {
         let raw_window_handles = RwLock::new(SmallVec::new());
         let settings = RefCell::new(WindowsPlatformSystemSettings::new());
         let icon = load_icon().unwrap_or_default();
+        let current_cursor = Cell::new(load_cursor(CursorStyle::Arrow));
         let inner = Rc::new(WindowsPlatformInner {
             background_executor,
             foreground_executor,
@@ -167,6 +170,7 @@ impl WindowsPlatform {
             dispatch_event,
             settings,
             icon,
+            current_cursor,
         });
         Self { inner }
     }
@@ -646,29 +650,7 @@ impl Platform for WindowsPlatform {
     }
 
     fn set_cursor_style(&self, style: CursorStyle) {
-        let handle = match style {
-            CursorStyle::IBeam | CursorStyle::IBeamCursorForVerticalLayout => unsafe {
-                load_cursor(IDC_IBEAM)
-            },
-            CursorStyle::Crosshair => unsafe { load_cursor(IDC_CROSS) },
-            CursorStyle::PointingHand | CursorStyle::DragLink => unsafe { load_cursor(IDC_HAND) },
-            CursorStyle::ResizeLeft | CursorStyle::ResizeRight | CursorStyle::ResizeLeftRight => unsafe {
-                load_cursor(IDC_SIZEWE)
-            },
-            CursorStyle::ResizeUp | CursorStyle::ResizeDown | CursorStyle::ResizeUpDown => unsafe {
-                load_cursor(IDC_SIZENS)
-            },
-            CursorStyle::OperationNotAllowed => unsafe { load_cursor(IDC_NO) },
-            _ => unsafe { load_cursor(IDC_ARROW) },
-        };
-        if handle.is_err() {
-            log::error!(
-                "Error loading cursor image: {}",
-                std::io::Error::last_os_error()
-            );
-            return;
-        }
-        let _ = unsafe { SetCursor(HCURSOR(handle.unwrap().0)) };
+        self.inner.current_cursor.set(load_cursor(style));
     }
 
     // todo(windows)
@@ -773,10 +755,6 @@ impl Drop for WindowsPlatform {
     }
 }
 
-unsafe fn load_cursor(name: PCWSTR) -> Result<HANDLE> {
-    LoadImageW(None, name, IMAGE_CURSOR, 0, 0, LR_DEFAULTSIZE | LR_SHARED).map_err(|e| anyhow!(e))
-}
-
 fn open_target(target: &str) {
     unsafe {
         let ret = ShellExecuteW(