Summary:
This patch fixes some of issues that the Snap Helper effect currently
has:
* If a window is being moved, there are visual artifacts (cause: missing
addRepaint's);
* It uses addRepaintFull;
* For some reason, if a window goes deleted, it will be kept around as
long as the Snap Helper effect needs it (visually, it doesn't look
good).
Among other changes:
* Use variables to store color and width of grid lines;
* Use new connect syntax;
* Port to TimeLine;
* Fix coding style in some places.
Test Plan:
Tried the effect with different rendering backends, no longer see visual
artifacts when moving or resizing windows.
Reviewers: #kwin, romangg
Reviewed By: #kwin, romangg
Subscribers: romangg, abetts, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D15695
47c8405388