Set and unset individual atoms in _NET_WM_STATE instead of overwriting the entire list everytime. This allows independent management of multiple states.

fixes #1873

testcases/t/253-multiple-net-wm-state-atoms.t

@@ -0,0 +1,70 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • http://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • http://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • http://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+#
+# Ticket: #1873
+use i3test;
+use X11::XCB qw(:all);
+
+sub get_wm_state {
+    sync_with_i3;
+    my $atom = $x->atom(name => '_NET_WM_STATE_HIDDEN');
+
+    my ($con) = @_; 
+    my $cookie = $x->get_property(
+        0,  
+        $con->{id},
+        $x->atom(name => '_NET_WM_STATE')->id,
+        GET_PROPERTY_TYPE_ANY,
+        0,  
+        4096
+    );  
+
+    my $reply = $x->get_property_reply($cookie->{sequence});
+    my $len = $reply->{length};
+    return 0 if $len == 0;
+
+    my @atoms = unpack("L$len", $reply->{value});
+    return \@atoms;
+}
+
+my $wm_state_sticky = $x->atom(name => '_NET_WM_STATE_STICKY')->id;
+my $wm_state_fullscreen = $x->atom(name => '_NET_WM_STATE_FULLSCREEN')->id;
+
+##########################################################################
+# Given a sticky container, when it is fullscreened, then both wm state
+# atoms are set. When the container is unfullscreened, then only the
+# sticky atom is still set.
+##########################################################################
+
+fresh_workspace;
+my $window = open_window;
+cmd 'sticky enable';
+is_deeply(get_wm_state($window), [ $wm_state_sticky ], 'sanity check: _NET_WM_STATE_STICKY is set');
+
+cmd 'fullscreen enable';
+is_deeply(get_wm_state($window), [ $wm_state_sticky, $wm_state_fullscreen ],
+    'both _NET_WM_STATE_FULLSCREEN and _NET_WM_STATE_STICKY are set');
+
+cmd 'sticky disable';
+is_deeply(get_wm_state($window), [ $wm_state_fullscreen ], 'only _NET_WM_STATE_FULLSCREEN is set');
+
+cmd 'sticky enable';
+cmd 'fullscreen disable';
+is_deeply(get_wm_state($window), [ $wm_state_sticky ], 'only _NET_WM_STATE_STICKY is set');
+
+##########################################################################
+
+done_testing;