Fixed event handlers new xid not displaying after saving edit form

[Patrykb0802]

When editing already created event handler after deleting xid and saving, completely new xid is generated but not shown until you re-choose that event handler

To Reproduce

1. Go to Event Handlers
2. Pick any event handler and save it
3. Select just saved event handler
4. Delete xid and save -> "Event Handler have been saved" -> No visible xid in editing form -> error

Expected behavior It should behave same way as when creating event handler, when you click save, new xid should appear automatically

Desktop:

• OS: Linux Mint
• Browser Chrome
• Version 2.7.6.1

Additional context Look for edit form refresh when creating event handler, applying same logic when saving edited event handler should get rid of this problem.