Created attachment 105823 [details] screenshot See the screenshot please. I'm running plasma 5.10 on Arch.
That's, well, interesting ... currently no idea.
Might have been related to the implicit size thing in IconItem? What plasma-framework version is this?
plasma-framework 5.34.
*** Bug 380958 has been marked as a duplicate of this bug. ***
FYI I am using Ultra Flat Icons (https://store.kde.org/p/1171748/ - my [bug #380958](https://bugs.kde.org/show_bug.cgi?id=380958) ).
I can confirm with Ultra-Flat-Icons
Patch https://phabricator.kde.org/D6751
Git commit d28deb6f4ab2f9e03b90f8e257145ffd793cb15d by Kai Uwe Broulik. Committed on 17/07/2017 at 14:15. Pushed by broulik into branch 'Plasma/5.10'. [Task Manager] Fix icon size in launcher tooltips Depending on icon theme the implicit size of the icon may be huge. FIXED-IN: 5.10.4 Differential Revision: https://phabricator.kde.org/D6751 M +2 -0 applets/taskmanager/package/contents/ui/ToolTipInstance.qml https://commits.kde.org/plasma-desktop/d28deb6f4ab2f9e03b90f8e257145ffd793cb15d
*** Bug 382571 has been marked as a duplicate of this bug. ***
I can confirm that this is not happening anymore.