core/modules/outside_in/outside_in.module | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/core/modules/outside_in/outside_in.module b/core/modules/outside_in/outside_in.module
index c397ffe..665468a 100644
--- a/core/modules/outside_in/outside_in.module
+++ b/core/modules/outside_in/outside_in.module
@@ -100,7 +100,14 @@ function outside_in_entity_type_build(array &$entity_types) {
  * Implements hook_preprocess_HOOK() for block templates.
  */
 function outside_in_preprocess_block(&$variables) {
-  // Only blocks that have an off_canvas form will have a "Quick Edit" link.
+  // Only blocks that have an off_canvas form will have a "Quick Edit" link. We
+  // could wait for the contextual links to be initialized on the client side,
+  // and then add the class and data- attribute below there (via JavaScript).
+  // But that means that it will be impossible to show Settings Tray's clickable
+  // regions immediately when the page loads. When latency is high, this will
+  // cause flicker. Therefore, for now, we choose to duplicate some logic to
+  // guarantee a smooth experience.
+  // This is an implementation detail that may change in the future.
   // @see \Drupal\outside_in\Access\BlockPluginHasOffCanvasFormAccessCheck
   if (\Drupal::service('plugin.manager.block')->createInstance($variables['plugin_id'])->hasFormClass('off_canvas')) {
     // Add class and attributes to all blocks to allow Javascript to target.