Improve integration with PowerDevil and libnotificationmanager

[romangg]

Introduction

Both daemons/libraries have a dependency on libkscreen. According to the maintainer of both projects:

• PowerDevil uses libkscreen to check when there is an external monitor connected to a laptop and then not go into standby should the laptop lid be shut.
• libnotificationmanager switches automatically in a "not-disturb" mode when an external monitor is connected. The assumption is that in such a case the user is likely holding a presentation.

Problem

While this should still work in KWinFT's X11 session it won't in KWinFT's Wayland session since libkscreen misses a respective plugin for Wrapland which is only provided by Disman.

Solution

Option 1: Ignore

Currently we ignore these two features. But at least the PowerDevil one seems quite essential for certain use cases.

Option 2: Fork PowerDevil

As established above at least the PowerDevil functionality is quite important. For that we could opt to fork PowerDevil and change the libkscreen code to Disman. At least at the moment the diff should be rather contained. But PowerDevil is a complicated project and it would be nicer to work together with its current upstream maintainer.

Option 3: Provide integration upstream

That would be the best long-term solution of course but it seems difficult since there would need to be some kind of plugin system in both consumers.

Option 4: Provide integration in KWinFT/Wrapland

KDE's outputmanagement protocol could be supported at least in a read-only way in Wrapland. Then libkscreen would still work.

Option 5: ...

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