remove Swing input map, which might bind keys in unexpected ways (e.g. LEFT/RIGHT in singleton list);
handle KP_UP/KP_DOWN keys as well, like Swing does;

--- a/NEWS	Wed Sep 04 11:12:00 2013 +0200
+++ b/NEWS	Wed Sep 04 12:20:00 2013 +0200
@@ -101,7 +101,7 @@
 
   - Light-weight popup, which avoids explicit window (more reactive
     and more robust).  Interpreted key events include TAB, ESCAPE, UP,
-    DOWN, PAGE_UP, PAGE_DOWN.  Uninterpreted key events are passed to
+    DOWN, PAGE_UP, PAGE_DOWN.  All other key events are passed to
     the jEdit text area.
 
   - Explicit completion via standard jEdit shortcut C+b, which has

--- a/src/Tools/jEdit/src/completion_popup.scala	Wed Sep 04 11:12:00 2013 +0200
+++ b/src/Tools/jEdit/src/completion_popup.scala	Wed Sep 04 12:20:00 2013 +0200
@@ -244,6 +244,11 @@
   list_view.peer.setVisibleRowCount(items.length min 8)
   list_view.peer.setSelectedIndex(0)
 
+  for (cond <-
+    List(JComponent.WHEN_FOCUSED,
+      JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT,
+      JComponent.WHEN_IN_FOCUSED_WINDOW)) list_view.peer.setInputMap(cond, null)
+
   private def complete_selected(): Boolean =
   {
     list_view.selection.items.toList match {
@@ -283,8 +288,8 @@
               case KeyEvent.VK_ESCAPE =>
                 hide_popup()
                 e.consume
-              case KeyEvent.VK_UP => move_items(-1); e.consume
-              case KeyEvent.VK_DOWN => move_items(1); e.consume
+              case KeyEvent.VK_UP | KeyEvent.VK_KP_UP => move_items(-1); e.consume
+              case KeyEvent.VK_DOWN | KeyEvent.VK_KP_DOWN => move_items(1); e.consume
               case KeyEvent.VK_PAGE_UP => move_pages(-1); e.consume
               case KeyEvent.VK_PAGE_DOWN => move_pages(1); e.consume
               case _ =>