what is the arrow called?

[Ralf Mardorf]

On Tue, 2014-11-11 at 21:35 +0100, Mathias Brodala wrote:
> Not sure if that's what you mean but the function it triggers is called
> "shading". It's based on the _NET_WM_ACTION_SHADE atom from the wm-spec[0].

Oops, my apologies, indeed the roll up and down function is called
shading, https://wiki.xfce.org/howto/xfwm4_theme , when you mentioned it
I remembered it :D.