KModifierKeyInfo usage and API

[David Faure]

We are still a bit unsure what to do about KModifierKeyInfo in KF5:

* It's currently only implemented on X11
(PovAddict says querying for modifiers on Windows is easy to add, but getting 
notified of changes seems quite problematic)

* The API (latching vs locking) seems to be a bit too X11 specific, it's 
unsure that these concepts exist on other platforms
(issue raised in http://git.reviewboard.kde.org/r/112443/#review41013)

* gwenview was ported away from it (a simple keyPress handler takes care of 
notifying the app that Ctrl was pressed)

* This leaves two users for KModifierKeyInfo as far as lxr.kde.org can see:

1) kile uses it to query the status of Caps Lock at the time when a key is 
pressed. It uses isKeyLatched()||isKeyLocked() so clearly it doesn't need the 
distinction.

2) Plasma's KeyService offers the KModifierKeyInfo API in the KeyStatesEngine.
Not sure how to then find the users of that.... general search on keystate 
found this:
http://lxr.kde.org/source/kde/kdeplasma-addons/applets/plasmaboard/widget.cpp
but I can't find the actual use of the engine in there?
Can a plasma developer tell me how to find the use of this stuff, to see how 
much we can change its API? Thanks.

-- 
David Faure, faure at kde.org, http://www.davidfaure.fr
Working on KDE, in particular KDE Frameworks 5