D18000: Tweak slidingpopups effect to make animation smoother

ngraham added a comment.


  @sefaeyeoglu thanks for this patch. We have a set of emerging guidelines for animations in D25343 <https://phabricator.kde.org/D25343>. Can you address the inline comments so we can push this forward?

INLINE COMMENTS

> slidingpopups.cpp:470
>      animation.timeLine.setDuration((*dataIt).slideInDuration);
> -    animation.timeLine.setEasingCurve(QEasingCurve::InOutSine);
> +    animation.timeLine.setEasingCurve(QEasingCurve::OutQuart);
>  

Let's make this `InQuad` to be consistent with most other animations in Plasma, and conform to the emerging guidelines in D25343 <https://phabricator.kde.org/D25343>.

REPOSITORY
  R108 KWin

REVISION DETAIL
  https://phabricator.kde.org/D18000

To: sefaeyeoglu, #vdg, zzag, #kwin
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