diff --git a/src/canvas.class.js b/src/canvas.class.js
index 96e603f3..d2b3d4da 100644
--- a/src/canvas.class.js
+++ b/src/canvas.class.js
@@ -154,8 +154,10 @@
      * Indicates which key enable alternative selection
      * in case of target overlapping with active object
      * values: 'altKey', 'shiftKey', 'ctrlKey'.
+     * For a series of reason that come from the general expectations on how
+     * things should work, this feature works only for preserveObjectStacking true.
      * If `null` or 'none' or any other string that is not a modifier key
-     * feature is disabled feature disabled.
+     * feature is disabled.
      * @since 1.6.5
      * @type null|String
      * @default