KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE’s software runs on GNU/Linux, BSD and other operating systems, including Windows.
If you encounter a bug, proceed to https://bugs.kde.org/, check whether it has been reported.
If it hasn't, report it yourself.
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Developers do not look for reports on social media, so they will not see it and all it does is clutter up the feed.
One of the KDE Plasma features I use almost in daily basis is the MouseMark.
Go to your settings, in Desktop Effects, Enable the MouseMark (you can change the settings of it in the button in front of it). Then press Meta+Shift and move your mouse to doodle, or press and release Meta+Shift+Ctrl to define beginning and end of an arrow (it will draw the rest.
Interestingly enough, it have been in Plasma for the past 16 years:
https://github.com/KDE/kde-workspace/tree/master/kwin/effects/mousemark
Interesting, I think there was a Firefox addon way back that did this and mouse gestures.
What do you use it for?