Fix shortcuts double-emitting from browser on Mac (#306198)

Author: kycutler

src/vs/platform/browserView/electron-browser/preload-browserView.ts

@@ -40,11 +40,45 @@
 			return;
 		}
 
-		// filter to events that either have modifiers or do not have a character representation.
-		if (!(event.ctrlKey || event.altKey || event.metaKey) && event.key.length === 1) {
+		const isNonEditingKey =
+			event.key === 'Escape' ||
+			/^F\d+$/.test(event.key) ||
+			event.key.startsWith('Audio') || event.key.startsWith('Media') || event.key.startsWith('Browser');
+
+		// Only forward if there's a command modifier or it's a non-editing key
+		// (most plain key events should just be handled natively by the browser and not forwarded)
+		if (!(event.ctrlKey || event.altKey || event.metaKey) && !isNonEditingKey) {
 			return;
 		}
 
+		const isMac = navigator.platform.indexOf('Mac') >= 0;
+
+		// Alt+Key special character handling (Alt + Numpad keys on Windows/Linux, Alt + any key on Mac)
+		if (event.altKey && !event.ctrlKey && !event.metaKey) {
+			if (isMac || /^Numpad\d+$/.test(event.code)) {
+				return;
+			}
+		}
+
+		// Allow native shortcuts (copy, paste, cut, undo, redo, select all) to be handled by the browser
+		const ctrlCmd = isMac ? event.metaKey : event.ctrlKey;
+		if (ctrlCmd && !event.altKey) {
+			const key = event.key.toLowerCase();
+			if (!event.shiftKey && (key === 'a' || key === 'c' || key === 'v' || key === 'x' || key === 'z')) {
+				return;
+			}
+			if (event.shiftKey && (key === 'v' || key === 'z')) {
+				return;
+			}
+			// Ctrl+Y is redo on Windows/Linux
+			if (!event.shiftKey && key === 'y' && !isMac) {
+				return;
+			}
+		}
+
+		// Everything else should be forwarded to the workbench for potential shortcut handling.
+		event.preventDefault();
+		event.stopPropagation();
 		ipcRenderer.send('vscode:browserView:keydown', {
 			key: event.key,
 			keyCode: event.keyCode,