Hello, 

there is the following issue with the Now Dock or the all new Latte Dock. As a reference both are docks that animate with parabolic zoom their tasks and plasmoids. They both use the QQuickWindow mask in order to free the areas of the window that are not needed from the dock.
We have the following issue and we are trying to understand whichone's responsibility is this case.

As you can see in the screenshot: https://cloud.githubusercontent.com/assets/24593950/22618122/43503764-ead5-11e6-9eb6-141bbd907b2e.png

when the parabolic zoom starts, the mask of the window increases directly to the maximum needed size but there are cases that the above painting is happening.

By reading at: http://doc.qt.io/qt-5/qwindow.html#setMask

Window manager responsibility: "The window manager may or may not choose to display any areas of the window not included in the mask"

Application responsibility: "it is the application's responsibility to clear to transparent the areas that are not part of the mask."

from our part we dont paint the areas outside the mask for the above screenshot to occur. Could you please provide with some wisdom, is this Qt, Kwin or our dock fault?

with regards,
michail