synedit: added note

git-svn-id: trunk@18163 -

components/synedit/syncompletion.pas

@@ -1313,6 +1313,7 @@ var
 begin
   //debugln('TSynCompletion.Validate ',dbgsName(Sender),' ',dbgs(Shift),' Position=',dbgs(Position));
   F := Sender as TSynBaseCompletionForm;
+  // Note: Form.Visible can be false, for example when completion only contains one item
   if F.CurrentEditor is TCustomSynEdit then
     with TCustomSynEdit(F.CurrentEditor) do begin
       BeginUndoBlock;