Spare borders when tiling

[Pétùr]

When tiling in Xfce (xfwm4 4.12.4-1 in Debian sid) I have some space left
at the bottom, left and right. The tiling is not border to border.
Windows are from xfce4-terminal and emacs. My ratio screen is
a popular one (16:9). I use the mouse to drag window to the border.

Is there anyway to have a proper tiling with no space left? Future
versions of Xfce are improving on this point?

Pétùr.