Summary:
Plasma's OSDs for volume/screens etc use PlasmaExtras.Heading, this
should to.
Also correct centering text to constrain the text element and align the
text within that bounding box. Previous code could have overflown in the
event of a really really long desktop name if we're resizing to the
grid.
BUG: 356600
Test Plan:
Switched desktop with OSD on
Tried with and without "show desktop layout indicators"
Reviewers: #kwin, graesslin
Reviewed By: #kwin, graesslin
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D16420
fe07909cd8