Hide code completion word list when close expression evaluator dialog.

1. Hi Lluis, I added a fix to hide completion window when closing the dialog. 
2. For the second one - the arrows do not working I found this: If you type "." the completion windows is opening and you can use arrows to navigate up and down, but if you continue typing name of field/property/method they stop working, after that arrows do not working at all even if you clear all text and start typing from scratch. 
I observe the same behavior in the watch pad, I am not so good with completion system and currently I can't fix it :(.