VSE: Don't draw unused properties in redo panel

Property `delete_data` was drawn in redo panel, when retiming key is
deleted, but this property is useful only when deleting strips.

source/blender/editors/space_sequencer/sequencer_edit.cc

@@ -1675,7 +1675,7 @@ static int sequencer_delete_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  if (sequencer_retiming_mode_is_active(C)) {
+  if (RNA_boolean_get(op->ptr, "use_retiming_mode")) {
     sequencer_retiming_key_remove_exec(C, op);
   }
 
@@ -1711,9 +1711,26 @@ static int sequencer_delete_invoke(bContext *C, wmOperator *op, const wmEvent *e
     }
   }
 
+  if (sequencer_retiming_mode_is_active(C)) {
+    RNA_boolean_set(op->ptr, "use_retiming_mode", true);
+  }
+
   return sequencer_delete_exec(C, op);
 }
 
+static bool sequencer_delete_poll_property(const bContext * /* C */,
+                                           wmOperator *op,
+                                           const PropertyRNA *prop)
+{
+  const char *prop_id = RNA_property_identifier(prop);
+
+  if (STREQ(prop_id, "delete_data") && RNA_boolean_get(op->ptr, "use_retiming_mode")) {
+    return false;
+  }
+
+  return true;
+}
+
 void SEQUENCER_OT_delete(wmOperatorType *ot)
 {
 
@@ -1726,6 +1743,7 @@ void SEQUENCER_OT_delete(wmOperatorType *ot)
   ot->invoke = sequencer_delete_invoke;
   ot->exec = sequencer_delete_exec;
   ot->poll = sequencer_edit_poll;
+  ot->poll_property = sequencer_delete_poll_property;
 
   /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
@@ -1737,6 +1755,13 @@ void SEQUENCER_OT_delete(wmOperatorType *ot)
                              "Delete Data",
                              "After removing the Strip, delete the associated data also");
   RNA_def_property_flag(ot->prop, PROP_SKIP_SAVE);
+
+  ot->prop = RNA_def_boolean(ot->srna,
+                             "use_retiming_mode",
+                             false,
+                             "Use Retiming Data",
+                             "Operate on retiming data instead of strips");
+  RNA_def_property_flag(ot->prop, PROP_HIDDEN);
 }
 
 /** \} */