#315 Edit field mnemonic in Firefox activates context help

[Miro Halas]

This was observed using Pattern test dialogtabtest4.
When user uses mnemonic (ALT+key) to move focus to one
of the edit controls, in Firefox the context help for
that field is activated as well (it can be hidden by
again using the menominc). In IE it works correctly and
only the focus moves to the field and no context help
is activated. This should behave in Firefox the same
way as it behaves in IE, that is only the focus should
be moved and no context help should be displayed.