adding new custom drag event handler to allow event bubbling

src/vs/workbench/contrib/webview/browser/webviewElement.ts

@@ -34,7 +34,7 @@ import { loadLocalResource, WebviewResourceResponse } from 'vs/workbench/contrib
 import { WebviewThemeDataProvider } from 'vs/workbench/contrib/webview/browser/themeing';
 import { areWebviewContentOptionsEqual, IWebview, WebviewContentOptions, WebviewExtensionDescription, WebviewInitInfo, WebviewMessageReceivedEvent, WebviewOptions } from 'vs/workbench/contrib/webview/browser/webview';
 import { WebviewFindDelegate, WebviewFindWidget } from 'vs/workbench/contrib/webview/browser/webviewFindWidget';
-import { FromWebviewMessage, KeyEvent, ToWebviewMessage } from 'vs/workbench/contrib/webview/browser/webviewMessages';
+import { DragEvent, FromWebviewMessage, KeyEvent, ToWebviewMessage } from 'vs/workbench/contrib/webview/browser/webviewMessages';
 import { decodeAuthority, webviewGenericCspSource, webviewRootResourceAuthority } from 'vs/workbench/contrib/webview/common/webview';
 import { IWorkbenchEnvironmentService } from 'vs/workbench/services/environment/common/environmentService';
 import { CodeWindow } from 'vs/base/browser/window';
@@ -310,6 +310,10 @@ export class WebviewElement extends Disposable implements IWebview, WebviewFindD
 			this._startBlockingIframeDragEvents();
 		}));
 
+		this._register(this.on('drag', (event) => {
+			this.handleDragEvent('drag', event);
+		}));
+
 		if (initInfo.options.enableFindWidget) {
 			this._webviewFindWidget = this._register(instantiationService.createInstance(WebviewFindWidget, this));
 		}
@@ -697,6 +701,17 @@ export class WebviewElement extends Disposable implements IWebview, WebviewFindD
 		this.window?.dispatchEvent(emulatedKeyboardEvent);
 	}
 
+	private handleDragEvent(type: 'drag', event: DragEvent) {
+		// Create a fake KeyboardEvent from the data provided
+		const emulatedDragEvent = new DragEvent(type, event);
+		// Force override the target
+		Object.defineProperty(emulatedDragEvent, 'target', {
+			get: () => this.element,
+		});
+		// And re-dispatch
+		this.window?.dispatchEvent(emulatedDragEvent);
+	}
+
 	windowDidDragStart(): void {
 		// Webview break drag and dropping around the main window (no events are generated when you are over them)
 		// Work around this by disabling pointer events during the drag.