Usability: Add Ctrl+Shift+F shortcut to search the main tracks database

[cr7pt0gr4ph7]

The new shortcut Ctrl+Shift+F (Search globally¹) compliments the existing shortcut Ctrl+F (Search in current location).

The use case for this is pretty simple (and motivated by me teaching dance classes) and probably pretty common elsewhere, too:

After digging around in my playlists & crates, leaving the computer to teach, and then coming back to it, I want to be able to quickly search for a specific song without having to first pick up the mouse or fiddle around with the trackpad.

Footnotes

1. Ok, it is only "globally" as long as all tracks are present in the main Mixxx database, and not contained in external libraries like iTunes or Rekordbox.² ↩

2. As a later improvement, one could extend Ctrl+Shift+F to, either:
   a. Actually initiate a global search over all available libraries, or:
   b. Make default library to which Ctrl+Shift+F jumps configurable in the preferences, or:
   c. Provide different shortcuts for the different external libraries. ↩

[ronso0]

Note that there is already Library::searchTracksInCollection (emitted when clicking actions in WSearchRelatedTracksMenu), which (IMHO) allows a much simpler implementation.

[cr7pt0gr4ph7]

@ronso0 Thanks, I will have a look! I'll have to place the shortcut handling somewehere else, though, so it also works when the search widget is disabled (this behavioris inherent to QShortcut). I'd use a custom key binding in KeyboardEventFilter, but then it'd only work when Keyboard shortcuts are enabled.

Sidenote: There seem to be at at least three ways to define keyboard shortcut actions and associated key sequences right now:

1. via eventFilter/keyPressEvent
2. via QShortcut/QAction
3. via KeyboardEventFilter/*.kbd.cfg/ControlObject (only active wjen

Option 3 is only active when keyboard shortcuts are enabled in the options, but when it is, it (mostly) overrides the other two.
Option 2 is somewhat integrated with option 3, but it's all bit convoluted.

Maybe it makes sense to integrate the "(Custom) keyboard shortcuts disabled" codepath into KeyboardEventFilter, too?

[ronso0]

How about adding "Search in Tracks" to the Library menu?
And add the shortcut hint to the searchbar tooltip?