- Removed subclassing in both implementations of `show_context_menu_f…

…or_hwnd`

- Removed `CONTEXT_MENU_SUBCLASS_ID` and `CONTEXT_SUMENU_SUBCLASS_ID` constants
- Adding entry in `.changes`

.changes/win32-context-menu-fixes

@@ -0,0 +1,13 @@
+---
+"muda": "patch"
+---
+
+These changes are to address a design flaw in how `muda` handles context menus on Windows.
+
+The normal way menus with `muda` are used on Windows is they get attached to a window, and the window is subclassed to intercept commands (`WM_COMMAND`) and some drawing behaviors (I'm not 100% sure on this, but this appears in place to support theming and dark mode).  When the `Menu` is dropped, it will be unattached from all windows and the subclasses will be removed.
+
+Context menus seem to follow a slightly different pattern.  When `show_context_menu_for_hwnd()` is called, the subclass is attached to the window, but never removed.  This behavior is problematic because the menu can be dropped without the subclass removed, causing a crash.  Furthermore, having this subclass attached unnecessarily is not necessarily a good idea.
+
+These changes to `muda` refactor menu support on Windows to remove the HWND subclassing when the context menu is active.
+
+These changes also address a memory leak where when an HWND is subclassed, the reference to the menu object was placed in a `Box` seemingly unnecessarily, and this `Box` never seems to be dropped.  This was changed to using straight references.

src/platform_impl/windows/mod.rs

@@ -413,22 +413,7 @@ impl Menu {
     }
 
     pub fn show_context_menu_for_hwnd(&mut self, hwnd: isize, position: Option<Position>) {
-        unsafe {
-            SetWindowSubclass(
-                hwnd as _,
-                Some(menu_subclass_proc),
-                CONTEXT_MENU_SUBCLASS_ID,
-                dwrefdata_from_obj(self),
-            );
-        }
         let rc = show_context_menu(hwnd as _, self.hpopupmenu, position);
-        unsafe {
-            RemoveWindowSubclass(
-                hwnd as _,
-                Some(menu_subclass_proc),
-                CONTEXT_MENU_SUBCLASS_ID,
-            );
-        }
         if let Some(item) = rc.and_then(|rc| self.find_by_id(rc)) {
             unsafe {
                 menu_selected(hwnd as _, &mut item.borrow_mut());
@@ -935,22 +920,7 @@ impl MenuChild {
     }
 
     pub fn show_context_menu_for_hwnd(&mut self, hwnd: isize, position: Option<Position>) {
-        unsafe {
-            SetWindowSubclass(
-                hwnd as _,
-                Some(menu_subclass_proc),
-                CONTEXT_SUBMENU_SUBCLASS_ID,
-                dwrefdata_from_obj(self),
-            );
-        }
         let rc = show_context_menu(hwnd as _, self.hpopupmenu, position);
-        unsafe {
-            RemoveWindowSubclass(
-                hwnd as _,
-                Some(menu_subclass_proc),
-                CONTEXT_SUBMENU_SUBCLASS_ID,
-            );
-        }
         if let Some(item) = rc.and_then(|rc| self.find_by_id(rc)) {
             unsafe {
                 menu_selected(hwnd as _, &mut item.borrow_mut());
@@ -1083,8 +1053,6 @@ unsafe fn obj_from_dwrefdata<T>(dwrefdata: usize) -> &'static mut T {
 const MENU_SUBCLASS_ID: usize = 200;
 const MENU_UPDATE_THEME: u32 = 201;
 const SUBMENU_SUBCLASS_ID: usize = 202;
-const CONTEXT_MENU_SUBCLASS_ID: usize = 203;
-const CONTEXT_SUBMENU_SUBCLASS_ID: usize = 204;
 
 unsafe extern "system" fn menu_subclass_proc(
     hwnd: windows_sys::Win32::Foundation::HWND,
@@ -1106,11 +1074,11 @@ unsafe extern "system" fn menu_subclass_proc(
             let id = util::LOWORD(wparam as _) as u32;
 
             let item = match uidsubclass {
-                MENU_SUBCLASS_ID | CONTEXT_MENU_SUBCLASS_ID => {
+                MENU_SUBCLASS_ID => {
                     let menu = obj_from_dwrefdata::<Menu>(dwrefdata);
                     menu.find_by_id(id)
                 }
-                SUBMENU_SUBCLASS_ID | CONTEXT_SUBMENU_SUBCLASS_ID => {
+                SUBMENU_SUBCLASS_ID => {
                     let menu = obj_from_dwrefdata::<MenuChild>(dwrefdata);
                     menu.find_by_id(id)
                 }