Impliment i3-style marks

This commit adds three commands to sway: `show_marks`, `mark` and
`unmark`. Marks are displayed right-aligned in the window border as i3
does. Marks may be found using criteria.

Fixes #1007

1 files changed, 13 insertions, 0 deletions

diff --git a/sway/commands/show_marks.c b/sway/commands/show_marks.c
new file mode 100644
index 00000000..ed56d9e5
--- /dev/null
+++ b/sway/commands/show_marks.c
@@ -0,0 +1,13 @@
+#include <string.h>
+#include <strings.h>
+#include "sway/commands.h"
+
+struct cmd_results *cmd_show_marks(int argc, char **argv) {
+        struct cmd_results *error = NULL;
+        if ((error = checkarg(argc, "show_marks", EXPECTED_EQUAL_TO, 1))) {
+                return error;
+        }
+
+        config->show_marks = !strcasecmp(argv[0], "on");
+        return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}