Add title attribute to user identifier (#29547)

src/components/structures/UserMenu.tsx

@@ -370,6 +370,13 @@ export default class UserMenu extends React.Component<IProps, IState> {
             ? toRightOf(this.state.contextMenuPosition)
             : below(this.state.contextMenuPosition);
 
+        const userIdentifierString = UserIdentifierCustomisations.getDisplayUserIdentifier(
+            MatrixClientPeg.safeGet().getSafeUserId(),
+            {
+                withDisplayName: true,
+            },
+        );
+
         return (
             <IconizedContextMenu {...position} onFinished={this.onCloseMenu} className="mx_UserMenu_contextMenu">
                 <div className="mx_UserMenu_contextMenu_header">
@@ -377,13 +384,8 @@ export default class UserMenu extends React.Component<IProps, IState> {
                         <span className="mx_UserMenu_contextMenu_displayName">
                             {OwnProfileStore.instance.displayName}
                         </span>
-                        <span className="mx_UserMenu_contextMenu_userId">
-                            {UserIdentifierCustomisations.getDisplayUserIdentifier(
-                                MatrixClientPeg.safeGet().getSafeUserId(),
-                                {
-                                    withDisplayName: true,
-                                },
-                            )}
+                        <span className="mx_UserMenu_contextMenu_userId" title={userIdentifierString || ""}>
+                            {userIdentifierString}
                         </span>
                     </div>