[Plasmoid Heading] Draw the heading only when there is an SVG in the theme
Summary:
We're the only theme with the appropriate heading svgs that make the headers and footers look as they should.
All the other themes fall back to Breeze, which is not a good look for some of them:
- the heading is too jarring compared to applet background
- the heading does not extend all the way vertically and horizontally
To solve this, to avoid degrading unmaintained themes and to give themes a chance to adjust on their own terms, this patch makes the heading visible only when the needed SVG exists in the theme.
Test Plan:
Avoids this:
Breeze still works as it should.
Reviewers: VDG, Plasma, niccolove, ngraham
Reviewed By: VDG, niccolove, ngraham
Subscribers: ngraham, niccolove, kde-frameworks-devel
Tags: Frameworks
Differential Revision: https://phabricator.kde.org/D29352
(cherry picked from commit 1b1018e687031166ecdcfa17a073cceada5b8100)