Cleanup: Clarify function name and comment logic

This is a bit tricky exceptional case, which originates to an original
motion tracking commit. Took a while to remember what it is ab out so
here is a comment for the future developers.

3 files changed, 10 insertions, 6 deletions

diff --git a/source/blender/editors/space_clip/clip_intern.h b/source/blender/editors/space_clip/clip_intern.h
index 90ede7e951b..8e1df133189 100644
--- a/source/blender/editors/space_clip/clip_intern.h
+++ b/source/blender/editors/space_clip/clip_intern.h
@@ -187,10 +187,10 @@ void clip_draw_sfra_efra(struct View2D *v2d, struct Scene *scene);
 
 /* tracking_ops.c */
 
-/* Find track in a proximity of the given event.
+/* Find track which can be slid in a proximity of the given event.
  * Uses the same rules w.r.t distance tolerances for track sliding and selection operators. */
-struct MovieTrackingTrack *tracking_find_track_in_proximity(struct bContext *C,
-                                                            const struct wmEvent *event);
+struct MovieTrackingTrack *tracking_find_slidable_track_in_proximity(struct bContext *C,
+                                                                     const struct wmEvent *event);
 
 void CLIP_OT_add_marker(struct wmOperatorType *ot);
 void CLIP_OT_add_marker_at_click(struct wmOperatorType *ot);
diff --git a/source/blender/editors/space_clip/tracking_ops.c b/source/blender/editors/space_clip/tracking_ops.c
index 260f56dfe9f..239e9925997 100644
--- a/source/blender/editors/space_clip/tracking_ops.c
+++ b/source/blender/editors/space_clip/tracking_ops.c
@@ -655,8 +655,8 @@ static MovieTrackingTrack *tracking_marker_check_slide(
   return NULL;
 }
 
-struct MovieTrackingTrack *tracking_find_track_in_proximity(struct bContext *C,
-                                                            const struct wmEvent *event)
+struct MovieTrackingTrack *tracking_find_slidable_track_in_proximity(struct bContext *C,
+                                                                     const struct wmEvent *event)
 {
   return tracking_marker_check_slide(C, event, NULL, NULL, NULL);
 }
diff --git a/source/blender/editors/space_clip/tracking_select.c b/source/blender/editors/space_clip/tracking_select.c
index 3ef32886995..5b2a1b945e7 100644
--- a/source/blender/editors/space_clip/tracking_select.c
+++ b/source/blender/editors/space_clip/tracking_select.c
@@ -405,8 +405,12 @@ static int select_invoke(bContext *C, wmOperator *op, const wmEvent *event)
   float co[2];
   const bool extend = RNA_boolean_get(op->ptr, "extend");
 
+  /* Special code which allows to slide a marker which belongs to currently selected but not yet
+   * active track. If such track is found activate it and return pass-though so that marker slide
+   * operator can be used immediately after.
+   * This logic makes it convenient to slide markers when left mouse selection is used. */
   if (!extend) {
-    MovieTrackingTrack *track = tracking_find_track_in_proximity(C, event);
+    MovieTrackingTrack *track = tracking_find_slidable_track_in_proximity(C, event);
     if (track != NULL) {
       MovieClip *clip = ED_space_clip_get_clip(sc);