This makes the api of EffectWindow more similar to the api of Window. It
also makes more sense to keep such signals in EffectWindow. In the future,
the effect window can be dropped in favor of the window.
Summary:
Effects that prefer to manipulate direction of animations sometimes need
to create animations in some particular state so later on they can be
played backward (swapping from and to is not enough and it would be wrong).
The proposed complete function lets such effects to fast-forward animations to
to the target position so they can be played backwards later on.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: davidedmundson, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D16450
