fix(windows): set WebView2 AllowExternalDrop to false (#1409)

* fix(windows): set WebView2 `AllowExternalDrop` to false

closes tauri-apps/tauri#11274

* remove accidental code

.changes/windows-drag-files.md

@@ -0,0 +1,5 @@
+---
+"wry": "patch"
+---
+
+On Windows, disable Webview2's file drop when using `WebViewBuilder::with_drag_drop_handler` which fix drag events for files from "Recent files" view.

src/webview2/drag_drop.rs

@@ -167,20 +167,29 @@ impl IDropTarget_Impl for DragDropTarget_Impl {
 
     let mut paths = Vec::new();
     let hdrop = unsafe { DragDropTarget::iterate_filenames(pDataObj, |path| paths.push(path)) };
+
+    let enter_is_valid = hdrop.is_some();
+
+    if !enter_is_valid {
+      return Ok(());
+    };
+
+    unsafe {
+      *self.enter_is_valid.get() = enter_is_valid;
+    }
+
     (self.listener)(DragDropEvent::Enter {
       paths,
       position: (pt.x as _, pt.y as _),
     });
 
-    unsafe {
-      let enter_is_valid = hdrop.is_some();
-      *self.enter_is_valid.get() = enter_is_valid;
+    let cursor_effect = if enter_is_valid {
+      DROPEFFECT_COPY
+    } else {
+      DROPEFFECT_NONE
+    };
 
-      let cursor_effect = if enter_is_valid {
-        DROPEFFECT_COPY
-      } else {
-        DROPEFFECT_NONE
-      };
+    unsafe {
       *pdwEffect = cursor_effect;
       *self.cursor_effect.get() = cursor_effect;
     }

src/webview2/mod.rs

@@ -134,7 +134,15 @@ impl InnerWebView {
       is_child,
     )?;
 
-    let drag_drop_controller = drop_handler.map(|handler| DragDropController::new(hwnd, handler));
+    let drag_drop_controller = drop_handler.map(|handler| {
+      // Disable file drops, so our handler can capture it
+      unsafe {
+        let _ = controller
+          .cast::<ICoreWebView2Controller4>()
+          .and_then(|c| c.SetAllowExternalDrop(false));
+      }
+      DragDropController::new(hwnd, handler)
+    });
 
     let w = Self {
       id,