Summary:
Currently, if user tries to move one of buttons to the left, ending up
dragging one button onto another, crash occurs.
In addition, this patch replaces verbose replacement(remove/insert) with
more elegant QVector<T>::move(int, int)
BUG: 374153
FIXED-IN: 5.8.7
Reviewers: graesslin, #kwin
Reviewed By: graesslin, #kwin
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D5117
The decoration button configuration interface is merged into the QML
part using two list views (left buttons, right buttons) and a grid
view for all the available buttons.
