[Task Manager] Fix sorting of tasks on last desktop in sort-by-desktop mode

Authored by hein on Mar 11 2019, 4:34 PM.

Description

[Task Manager] Fix sorting of tasks on last desktop in sort-by-desktop mode

Summary: BUG:404572

Reviewers: Plasma, mart

Reviewed By: Plasma, mart

Subscribers: asturmlechner, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D19259