Add 'mark' as allowed key to i3-save-tree output

diff --git a/i3-save-tree b/i3-save-tree
index add4c8c1c305ee8cc635fc6d4ff0cb24fad1097f..c64fc72a09ae119b6cd3bc8615781c3595be1551 100755 (executable)
--- a/i3-save-tree
+++ b/i3-save-tree
@@ -92,6 +92,7 @@ my %allowed_keys = map { ($_, 1) } qw(
     name
     geometry
     window_properties
+    mark
 );
 
 sub strip_containers {