RichText: Fix dead key input on Windows (#37777)

packages/rich-text/src/component/use-space.js

@@ -21,13 +21,38 @@ export function useSpace() {
 				return;
 			}
 
-			const { keyCode, altKey, metaKey, ctrlKey } = event;
+			const { keyCode, altKey, metaKey, ctrlKey, key } = event;
 
 			// Only consider the space key without modifiers pressed.
 			if ( keyCode !== SPACE || altKey || metaKey || ctrlKey ) {
 				return;
 			}
 
+			// Disregard character composition that involves the Space key.
+			//
+			// @see https://github.com/WordPress/gutenberg/issues/35086
+			//
+			// For example, to input a standalone diacritic (like ´ or `) using a
+			// keyboard with dead keys, one must first press the dead key and then
+			// press the Space key.
+			//
+			// Many operating systems handle this in such a way that the second
+			// KeyboardEvent contains the property `keyCode: 229`. According to the
+			// spec, 229 allows the system to indicate that an Input Method Editor
+			// (IDE) is processing some key input.
+			//
+			// However, Windows doesn't use `keyCode: 229` for dead key composition,
+			// instead emitting an event with values `keyCode: SPACE` and `key: '´'`.
+			// That is why checking the `key` property for values other than `SPACE`
+			// is important.
+			//
+			// This should serve as a reminder that the `KeyboardEvent.keyCode`
+			// attribute is officially deprecated and that we should consider more
+			// consistent interfaces.
+			if ( key !== ' ' ) {
+				return;
+			}
+
 			event.target.ownerDocument.execCommand( 'insertText', false, ' ' );
 			event.preventDefault();
 		}