Qemu boots to a black screen with XFCE4

Today I wanted to run XFCE4 to test something, but only got a black screen in Qemu.

Log:

X.Org X Server 1.20.5
X Protocol Version 11, Revision 0
Build Operating System: Linux 4.14.89-0-vanilla x86_64 Alpine Linux
Current Operating System: Linux qemu-amd64 5.1.5 #2-postmarketOS PREEMPT Sat Sep 14 05:03:28 UTC 2019 x86_64
Kernel command line: 'console=tty1 console=ttyS0 PMOS_NO_OUTPUT_REDIRECT PMOS_FORCE_PARTITION_RESIZE'
Build Date: 31 May 2019  06:22:13AM
 
Current version of pixman: 0.38.4
	Before reporting problems, check http://wiki.x.org
	to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
	(++) from command line, (!!) notice, (II) informational,
	(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Fri Aug 23 08:46:01 2019
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
(II) modeset(0): Initializing kms color map for depth 24, 8 bpc.
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Unsupported high keycode 372 for name <I372> ignored
>                   X11 cannot support keycodes above 255.
>                   This warning only shows for the first high keycode.
Errors from xkbcomp are not fatal to the X server
/usr/bin/startxfce4: X server already running on display :0
<stdin>:0: warning: Unknown encoding: C.UTF-8
    xfce4-session: No GPG agent found

(xfce4-session:1650): xfce4-session-WARNING **: 08:46:01.614: xfsm_manager_load_session: Something wrong with /home/bart/.cache/sessions/xfce4-session-qemu-amd64:0, Does it exist? Permissions issue?

(wrapper-2.0:1703): Gtk-WARNING **: 08:46:02.967: gtk_widget_size_allocate(): attempt to allocate widget with width -3 and height 48

(wrapper-2.0:1702): Gtk-WARNING **: 08:46:02.978: gtk_widget_size_allocate(): attempt to allocate widget with width -1 and height 50

(wrapper-2.0:1702): Gtk-WARNING **: 08:46:02.978: Negative content width -1 (allocation 1, extents 1x1) while allocating gadget (node border, owner GtkFrame)

(wrapper-2.0:1704): Gtk-WARNING **: 08:46:03.005: Negative content width -1 (allocation 1, extents 1x1) while allocating gadget (node button, owner XfceArrowButton)

** (lxpolkit:1720): CRITICAL **: 08:46:03.095: polkit_agent_listener_register_with_options: assertion 'POLKIT_IS_SUBJECT (subject)' failed

(lxpolkit:1720): GLib-GObject-CRITICAL **: 08:46:03.095: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

(nm-applet:1715): libnotify-WARNING **: 08:46:03.290: Failed to connect to proxy

(nm-applet:1715): nm-applet-WARNING **: 08:46:03.291: Failed to show notification: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.Notifications was not provided by any .service files