add testcase for the fullscreen restart problem of the previous commit

testcases/t/68-regress-fullscreen-restart.t

@@ -0,0 +1,28 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Verifies that i3 survives inplace restarts with fullscreen containers
+#
+use i3test;
+use X11::XCB qw(:all);
+use X11::XCB::Connection;
+
+my $x = X11::XCB::Connection->new;
+
+fresh_workspace;
+
+open_standard_window($x);
+open_standard_window($x);
+
+cmd 'layout stacking';
+sleep 1;
+
+cmd 'fullscreen';
+sleep 1;
+
+cmd 'restart';
+sleep 1;
+
+does_i3_live;
+
+done_testing;