Make Ctrl+F not toggle the search mode but always enable it.

Switching back from other applications, the previous behavior of Ctrl+F
would often bother you in that it would dismiss the search widget if it
was already enabled when you meant by the key you wanted to perform a
search.

Making Ctrl+F always set you in search mode should save user from having
to care about the mode which is persistent across application switching
and database locking.