diff --git a/gnome-shell-extensions.changes b/gnome-shell-extensions.changes
index 5f4e9f7..44d48ca 100644
--- a/gnome-shell-extensions.changes
+++ b/gnome-shell-extensions.changes
@@ -1,3 +1,11 @@
+-------------------------------------------------------------------
+Fri Sep 22 08:44:34 UTC 2017 - dimstar@opensuse.org
+
+- Register SLE-Classic with u-a handler for default.desktop
+  implementation, which obsoletes the change in
+  /etc/sysconfig/windowmanager to pick the 'default window manager'
+  (boo#1039756).
+
 -------------------------------------------------------------------
 Mon Sep 18 06:38:10 UTC 2017 - xwang@suse.com
 
diff --git a/gnome-shell-extensions.spec b/gnome-shell-extensions.spec
index f714487..028ac37 100644
--- a/gnome-shell-extensions.spec
+++ b/gnome-shell-extensions.spec
@@ -18,7 +18,6 @@
 
 
 %global __requires_exclude typelib\\(Meta\\)
-
 Name:           gnome-shell-extensions
 Version:        3.26.0
 Release:        0
@@ -41,15 +40,15 @@ Patch3:         sle-classic-lock-screen-background.patch
 Patch1000:      gse-sle-classic-ext.patch
 # Needed because we build a tarball generated with "git archive"
 BuildRequires:  gnome-common
-# Needed for directory ownership
-BuildRequires:  gnome-shell
 # gobject-introspection is needed for the typelib() rpm magic.
 BuildRequires:  gnome-patch-translation
+# Needed for directory ownership
+BuildRequires:  gnome-shell
 BuildRequires:  gobject-introspection
 BuildRequires:  intltool
+BuildRequires:  pkgconfig
 BuildRequires:  translation-update-upstream
 BuildRequires:  pkgconfig(gio-2.0)
-BuildRoot:      %{_tmppath}/%{name}-%{version}-build
 BuildArch:      noarch
 
 %description
@@ -92,8 +91,8 @@ menu, and provides the ability to hibernate.
 This package provides the extensions required to switch to gnome-shell classic
 and also installs the required session files.
 
-
 %lang_package -n %{name}-common
+
 %prep
 %setup -q
 %if !0%{?is_opensuse}
@@ -107,7 +106,7 @@ gnome-patch-translation-prepare
 ##gnome-patch-translation-update
 # In openSUSE GNOME, we don't launch gnome-session directly, but wrap this through a shell script, /usr/bin/gnome
 sed -i "s:Exec=gnome-session:Exec=gnome:g" data/gnome-classic.desktop.in
-cp %{S:1} .
+cp %{SOURCE1} .
 %if !0%{?is_opensuse}
 sed -i -e 's/openSUSE/SUSE Linux Enterprise/g' README.SUSE
 %endif
@@ -126,13 +125,29 @@ make %{?_smp_mflags}
 %make_install
 %find_lang %{name} %{?no_lang_C}
 %if !0%{?is_opensuse}
-install -m0644 %{S:2} %{buildroot}/%{_datadir}/xsessions/sle-classic.desktop
+install -m0644 %{SOURCE2} %{buildroot}/%{_datadir}/xsessions/sle-classic.desktop
 # Install SLE theme
 tar -xzvf %{SOURCE3}
 install -d %{buildroot}%{_datadir}/gnome-shell/theme
 cp SLE-theme/theme/*  %{buildroot}%{_datadir}/gnome-shell/theme
+
+# Prepare for 'default.desktop' being update-alternative handled, boo#1039756
+mkdir -p %{buildroot}%{_sysconfdir}/alternatives
+touch %{buildroot}%{_sysconfdir}/alternatives/default-xsession.desktop
+ln -s %{_sysconfdir}/alternatives/default-xsession.desktop %{buildroot}%{_datadir}/xsessions/default.desktop
 %endif
 
+%if !0%{?is_opensuse}
+%post -n gnome-shell-classic
+%{_sbindir}/update-alternatives --install %{_datadir}/xsessions/default.desktop \
+  default-xsession.desktop %{_datadir}/xsessions/sle-classic.desktop 30
+
+%postun -n gnome-shell-classic
+[ -f %{_datadir}/xsessions/sle-classic.desktop ] || %{_sbindir}/update-alternatives \
+  --remove default-xsession.desktop %{_datadir}/xsessions/sle-classic.desktop
+%endif
+
+
 %files common
 %defattr(-,root,root)
 %doc COPYING README.SUSE
@@ -164,8 +179,10 @@ cp SLE-theme/theme/*  %{buildroot}%{_datadir}/gnome-shell/theme
 %{_datadir}/gnome-shell/theme/gnome-classic-high-contrast.css
 %{_datadir}/xsessions/gnome-classic.desktop
 %if !0%{?is_opensuse}
+%{_datadir}/xsessions/default.desktop
 %{_datadir}/xsessions/sle-classic.desktop
 %{_datadir}/gnome-shell/theme/sle-background.png
+%ghost %{_sysconfdir}/alternatives/default-xsession.desktop
 %endif
 
 %files common-lang -f %{name}.lang