Margin in xfce4-panel's Gtk3 tasklist

[dreieinhalb]

This issue refers to commit 73f9fec

I'm not sure if the behaviour is intended or if this is a bug:

In the linked commit there is set a margin of 1px for tasklist buttons. My panel is at the top of the screen and when the mouse pointer is at the very top of the screen the tasklist buttons don't react so I have to move the mouse one pixel downwards. For me this is really annoying.