Fixes #82310 by adding a Ext.Msg.wait dialog before the submit is done and hiding it when the callback or fallback is called after the server answers.

Also, code improvements have been applied based on JSHint suggestions.
Merge pull request #131 from luisromangz/8.5-SNAPSHOT-82310

Fixes #82310 by adding a Ext.Msg.wait dialog before the submit is done a...