Sets form's target to `_blank` when submitted via Ctrl + Left Mouse Button or Ctrl + Enter.
当前为
Useful for "saving" form state in preceding tab.
Ctrl enter will work alike where plain enter would submit form (ie NOT on textareas).
Sadly, using middle mouse button for the same purpose does not work that well, because it would require invoking "artificial" form.submit(), what in case form targets got recently changed triggers popup blocker.
