Tweak default icewm preferences

Attention: this patch is applied in the %build phase, because it patches
a file generated by ./src/genpref. To edit the patch:

  quilt setup icewm.spec
  cd icewm-<version>
  quilt push -a
  ./configure <options from the spec>
  make -C src genpref
  ./src/genpref >src/preferences
  quilt import -p0 patches/icewm-preferences.patch
  quilt push
  vi lib/preferences
  quilt refresh
---
 src/preferences |   6 ++++++
 1 file changed, 6 insertions(+)

Index: src/preferences
===================================================================
--- a/src/preferences
+++ b/src/preferences
@@ -543,6 +543,7 @@
 
 #  Icon search path (colon separated)
 # IconPath="/usr/share/icons/hicolor:/usr/share/icons:/usr/share/pixmaps"
+IconPath="/usr/share/icons/Adwaita/16x16/apps:/usr/share/icons/hicolor:/usr/share/icons:/usr/share/pixmaps"
 
 #  Mailbox path (use $MAIL instead)
 # MailBoxPath=""
@@ -558,6 +559,7 @@
 
 #  Command to lock display/screensaver
 # LockCommand=""
+LockCommand="xlock -mousemotion"
 
 #  Command to run on clock
 # ClockCommand="xclock -name icewm -title Clock"
@@ -582,9 +584,11 @@
 
 #  Command to shutdown the system
 # ShutdownCommand="/bin/sh -c "{ test -e /run/systemd/system && systemctl poweroff; } ||:""
+ShutdownCommand="/bin/sh -c 'systemctl poweroff ||:'"
 
 #  Command to reboot the system
 # RebootCommand="/bin/sh -c "{ test -e /run/systemd/system && systemctl reboot; } ||:""
+RebootCommand="/bin/sh -c 'systemctl reboot ||:'"
 
 #  Command to run on CPU status
 # CPUStatusCommand="xterm -name top -title Process\ Status -e top"
@@ -1362,12 +1366,14 @@
 
 #  Desktop background scaled to full screen
 # DesktopBackgroundScaled=0 # 0/1
+DesktopBackgroundScaled=1 # 0/1
 
 #  Desktop background color
 # DesktopBackgroundColor="rgb:00/20/40"
 
 #  Desktop background image
 # DesktopBackgroundImage=""
+DesktopBackgroundImage="BRANDING_PICTURE"
 
 #  Color to announce for semi-transparent windows
 # DesktopTransparencyColor=""