Fix left/right cursor keys in TextArea

Since commit 5dc805c8

 key events for left/right cursor
get eaten by the MenuBar. That means, the events shouldn't be accepted
if no menu is shown.

Change-Id: Icc249a3c4d96e19e8c902276938a2972cf1364d9
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>

src/controls/MenuBar.qml

@@ -176,6 +176,8 @@ MenuBarPrivate {
             if (d.openedMenuIndex > 0) {
                 d.preselectMenuItem = true
                 d.openedMenuIndex--
+            } else {
+                event.accepted = false;
             }
         }
 
@@ -183,6 +185,8 @@ MenuBarPrivate {
             if (d.openedMenuIndex !== -1 && d.openedMenuIndex < root.menus.length - 1) {
                 d.preselectMenuItem = true
                 d.openedMenuIndex++
+            } else {
+                event.accepted = false;
             }
         }