Summary: It works for the effect
Test Plan:
kcmshell5 kcm_kwin_effects
Change some settings, the "Restore defaults" button is enabled when the state is not the default state.
Open an effect configuration, the "Restore defaults" button is enabled when the settings are not default.
Reviewers: #kwin, crossi, ervin, zzag
Reviewed By: #kwin, zzag
Subscribers: zzag, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D26040
cc4d191a94