Accessibility Checker losses some functionallity after making a quickfix

[mlewand]

This is a regression, most likely introduced in a05804a (#38).

After performing a quick fix, the Accessibility Icon in toolbar is disabled. Therefore I assume Controller.enabled is changed.

1. Open any sample with Accessibility Checker. (i.e. plugins/a11ychecker/dev/sample.html)
2. Navigate to the first issue which supports quick fixes.
3. Apply quick fix.

Expected result:
Checker should remain in checking mode. Toolbar icon should indicate that Accessibility Checker is on.

Current result:
The icon goes off, as if Accessibilty Checker would be disabled.

Additional info:

1. I guess it might be a good idea to see if it's possible not to close balloon each time we change focused issue, but only update its contents.

[mlewand]

Alright, so the reason for that problem was that when we were moving to the other issue the balloon was hidden and shown once again.

When it was hidden, the element which had a focus was firing a blur event, which in turn (with some timeout) caused the editor#blur event.

In result, according to changes in #38 it was closing the Accessibility Checker too soon.

I decided to put focus back to the editor while hiding a balloon, that makes sense, since always we want to go back to editing.