xfce 4.16 problem with external monitor

[Manfred Rebentisch]

Hello,

I use on Manjaro:

$ xfwm4 --version
	This is xfwm4 version 4.16.1 (revision 5f61a84ad) for Xfce 4.16
	Released under the terms of the GNU General Public License.
	Compiled against GTK+-3.24.29, using GTK+-3.24.30.

	Build configuration and supported features:
	- Startup notification support:                 Yes
	- XSync support:                                Yes
	- Render support:                               Yes
	- Xrandr support:                               Yes
	- Xpresent support:                             Yes
	- X Input 2 support:                            No
	- Embedded compositor:                          Yes
	- Epoxy support:                                Yes
	- KDE systray proxy (deprecated):               No


I want to close the laptop monitor and use the external monitor only.
With XUbuntu 18.04 it has worked perfect, but now there is no option. I
I close the laptop then the external monitor going black, system is in
suspend mode.

Can I change this behaviour?

Regards
Manfred

-- 
Manfred Rebentisch
Sarensecker Weg 26
29456 Hitzacker