Bug 485298

SUMMARY

There are several cases of misconfigurations, who lead to parts of the monitor setup, or the entirety of it, as inaccessible. 
Those are major issues, since essentially the entire installation of the OS is not usable anymore, or certain hardware with that installation. I raised one proposal, that aims to prevent that by introducing a countdown/confirmation button to the OSD widget. Still, by accidentally confirming such an ill setup, this issue could occur as well. Also, the confirmation countdown could render the OSD/Plasma widget as cumbersome, since it is intended to provide a quick and easy way, to change the output device. 

This proposal intents to detect ill setups and automatically corrects them. 

Currently, KScreen and KWin are completely fine with establishing a connection, that results in a black screen so long as it had been confirmed by the KScreen KCM before. 

That results in several issues, where KScreen connects to a device, that is not showing any content, while simultaneously applying the ill configuration. So KScreen/Kwin definitely detects the hardware, and does act upon it, despite the hardware not showing any content. 

I am confident, that we can simply restore to a healthy default, when we detect that the output is not displayed at all?

Or do (some) displays not even report this back? 
I mean, isnt there a way to read the resolution, etc, which would - assumingly - not be valid? 

Or maybe the refresh rate? 
Are there really displays out there, who report the values we might expect, despite not showing anything?
Including my very own internal laptop display?

Reference list: 

First issue: https://bugs.kde.org/show_bug.cgi?id=485269
Second issue: https://bugs.kde.org/show_bug.cgi?id=484592
Countdown feature proposal: https://bugs.kde.org/show_bug.cgi?id=485285

Thanks a lot