+##############################################################
+# 4: mark a con, use same mark to mark another con,
+# check that only the latter is marked
+##############################################################
+
+my $first = open_window;
+my $second = open_window;
+
+cmd 'mark important';
+cmd 'focus left';
+cmd 'mark important';
+
+is(get_mark_for_window_on_workspace($tmp, $first), 'important', 'first container now has the mark');
+ok(!get_mark_for_window_on_workspace($tmp, $second), 'second container lost the mark');
+
+##############################################################
+# 5: mark a con, toggle the mark, check that the mark is gone
+##############################################################
+
+my $con = open_window;
+cmd 'mark important';
+cmd 'mark --toggle important';
+ok(!get_mark_for_window_on_workspace($tmp, $con), 'container no longer has the mark');
+
+##############################################################
+# 6: toggle a mark on an unmarked con, check it is marked
+##############################################################
+
+my $con = open_window;
+cmd 'mark --toggle important';
+is(get_mark_for_window_on_workspace($tmp, $con), 'important', 'container now has the mark');
+
+##############################################################
+# 7: mark a con, toggle a different mark, check it is marked
+# with the new mark
+##############################################################
+
+my $con = open_window;
+cmd 'mark boring';
+cmd 'mark --toggle important';
+is(get_mark_for_window_on_workspace($tmp, $con), 'important', 'container has the most recent mark');
+
+##############################################################
+# 8: mark a con, toggle the mark on another con,
+# check only the latter has the mark
+##############################################################
+
+my $first = open_window;
+my $second = open_window;
+
+cmd 'mark important';
+cmd 'focus left';
+cmd 'mark --toggle important';
+
+is(get_mark_for_window_on_workspace($tmp, $first), 'important', 'left container has the mark now');
+ok(!get_mark_for_window_on_workspace($tmp, $second), 'second containr no longer has the mark');
+