[libhandy/wip/haecker-felix/flap-widget] Add a comment about the transition weirdness

[Alexander Mikhaylenko <alexm src gnome org>]

commit 8f9d6948ef8725702f406017fc818fc60c613b14
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu Nov 19 16:02:36 2020 +0500

    Add a comment about the transition weirdness

 src/hdy-flap.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/hdy-flap.c b/src/hdy-flap.c
index cc9758e3..246b1c49 100644
--- a/src/hdy-flap.c
+++ b/src/hdy-flap.c
@@ -254,6 +254,10 @@ set_folded (HdyFlap  *self,
 
   gtk_widget_queue_allocate (GTK_WIDGET (self));
 
+   /* When unlocked, folding should also hide flap. We don't want two concurrent
+    * animations in this case, instead only animate reveal and schedule a fold
+    * after it finishes, which will be skipped because the flap is fuly hidden.
+    * Meanwhile if it's unfolding, animate folding immediately. */
   if (!self->locked && folded)
     self->schedule_fold = TRUE;
   else