Autocomplete on issue links, user pickers, etc. should be cancelled when form field is exited

At the moment, JIRA's autocomplete isn't very useful for fast typists because it appears slowly on large servers like JAC. But the more irritating problem is that when a slow response comes back for the autocomplete, it can pop up after you've left the autocomplete field, obscuring other content on the form.

I'd suggest one of two possible implementation fixes:

• when the autocomplete returns, check whether the relevant field is active before displaying the dropdown
• when the field is blurred (loses focus), cancel any outstanding autocomplete actions on that field.