Enable the touchpad indicator in system tray settings and click on its icon. Watch the video please. I'm running plasma 5.9 beta on Arch. https://www.youtube.com/watch?v=Gql9Y-_2yxk
This bug looks related to bug 365630.
Somewhat related to Bug 365630 but the touchpad KCM switches from ActiveStatus to AcceptingInputStatus which causes System Tray to re-assess its visibility and then moves it to the front, although its effective visibility didn't actually change.
Git commit a7d56be57a1c1258608d8eb363191d69f40c12e3 by Kai Uwe Broulik. Committed on 08/02/2017 at 16:26. Pushed by broulik into branch 'master'. [System Tray] Introduce "effectiveStatus" property and update visibility only when that changes Instead of calling it in response to any of the properties it depends on. This also saves some calls to this function on startup (80 instead of 90 for me with 14 tray icons) and keeps plasmoids from shifting around just because their status changed from e.g. Active to AcceptingInput (like touchpad when it asks for whether you really want to disable touchpad with no mouse attached) although the item's effective visibility didn't actually change. Related: bug 365630 FIXED-IN: 5.10.0 Differential Revision: https://phabricator.kde.org/D4488 M +10 -4 applets/systemtray/package/contents/ui/items/AbstractItem.qml M +7 -8 applets/systemtray/package/contents/ui/main.qml https://commits.kde.org/plasma-workspace/a7d56be57a1c1258608d8eb363191d69f40c12e3