Ultimately this was due to missing nullptr check before trying to
process the image, but this should have been caught when loading
ImBufAnims. If any is missing, cancel multiview loading and load
movie as if it was single view only.

@@ -946,2 +946,4 @@
   }
 
+  if (!USER_VERSION_ATLEAST(402, 19)) {
+    userdef->sequencer_editor_flag |= USER_SEQ_ED_SIMPLE_TWEAKING;

@@ -230,6 +246,9 @@ static int change_frame_invoke(bContext *C, wmOperator *op, const wmEvent *event
   if (CTX_wm_space_seq(C) != nullptr && region->regiontype == RGN_TYPE_PREVIEW) {
     return OPERATOR_CANCELLED;
   }
+  if (sequencer_skip_for_handle_tweak(C, event)) {

@@ -46,3 +49,3 @@
 void ED_sequencer_special_preview_set(bContext *C, const int mval[2]);
 void ED_sequencer_special_preview_clear();
-bool sequencer_retiming_mode_is_active(const bContext *C);
+bool sequencer_retiming_mode_is_active(const Scene *scene);

@@ -1 +1 @@
-Subproject commit 0b910c0a718a1d54d07ecf95c63617576ee9a847
+Subproject commit 7181d6dccb9fe4184340f9f5b1c381f8089fe4ec

@@ -51,0 +54,4 @@
+ *
+ * r_seq1 first strip to be selected. Never nullptr if function returns true
+ * r_seq2 second strip to be selected.
+ * r_side which handle is selected. This further clarifies result if seq2 is nullptr.

@@ -51,0 +56,4 @@
+ * r_seq2 second strip to be selected.
+ * r_side which handle is selected. This further clarifies result if seq2 is nullptr.
+ */
+bool ED_sequencer_handle_selection_refine(const struct Scene *scene,

@@ -894,0 +982,4 @@
+    return false;
+  });
+
+  /* It may be better to sort strips, as there can be very small strip in set, that may not be

@@ -894,0 +1026,4 @@
+  return SEQ_SIDE_NONE;
+}
+
+static bool both_handles_are_selected(const Scene *scene,

@@ -645,6 +647,93 @@ static void sequencer_main_region_message_subscribe(const wmRegionMessageSubscri
   }
 }
 
+static bool mouseover_retiming_key(const Scene *scene,

@@ -648,0 +701,4 @@
+
+  int side;
+  Sequence *seq1, *seq2;
+  ED_sequencer_handle_selection_refine(scene, &region->v2d, mouse_co_view, &seq1, &seq2, &side);

@@ -383,6 +446,11 @@ void initMouseInputMode(TransInfo *t, MouseInput *mi, MouseInputMode mode)
         t->flag |= T_MODAL_CURSOR_SET;
         WM_cursor_modal_set(win, WM_CURSOR_NSEW_SCROLL);
       }
+      /* On ly use special cursor, when tweaking strips with mouse. */

@@ -17,0 +19,4 @@
+
+enum eSeqHandle {
+  SEQ_HANDLE_NONE = 0,
+  SEQ_HANDLE_LEFT = SEQ_LEFTSEL,

@@ -17,0 +24,4 @@
+  SEQ_HANDLE_BOTH,
+};
+
+struct StripSelection {

@@ -101,3 +101,3 @@
 #define RETIME_KEY_MOUSEOVER_THRESHOLD (16.0f * UI_SCALE_FAC)
 
-static rctf retiming_keys_box_get(const Scene *scene, const View2D *v2d, const Sequence *seq)
+rctf retiming_keys_box_get(const Scene *scene, const View2D *v2d, const Sequence *seq)

@@ -897,0 +992,4 @@
+    if (seq->machine != int(mouse_co[1])) {
+      continue;
+    }
+    if (min_ii(SEQ_time_left_handle_frame_get(scene, seq), SEQ_time_start_frame_get(seq)) >

@@ -897,0 +1018,4 @@
+  if (strips.size() == 2 && strip_to_frame_distance(scene, v2d, strips[0], mouse_co[0]) <
+                                strip_to_frame_distance(scene, v2d, strips[1], mouse_co[0]))
+  {
+    SWAP(Sequence *, strips[0], strips[1]);

@@ -897,0 +1034,4 @@
+  return s1_right == s2_left || s1_left == s2_right;
+}
+
+static eSeqHandle handle_selection_refine(const Scene *scene,

@@ -897,0 +1051,4 @@
+  return SEQ_HANDLE_NONE;
+}
+
+static bool both_handles_are_selected(const Scene *scene,

@@ -897,0 +1054,4 @@
+static bool both_handles_are_selected(const Scene *scene,
+                                      const Sequence *seq1,
+                                      const Sequence *seq2,
+                                      eSeqHandle seq1_side,

@@ -897,0 +1058,4 @@
+                                      const View2D *v2d,
+                                      float mouse_co[2])
+{
+  if ((U.sequencer_editor_flag & USER_SEQ_ED_SIMPLE_TWEAKING) == 0) {

@@ -897,0 +1067,4 @@
+  if (!strips_are_adjacent(scene, seq1, seq2)) {
+    return false;
+  }
+  const int seq2_side = handle_selection_refine(scene, seq2, v2d, mouse_co);

@@ -940,2 +1148,3 @@
+  StripSelection selection;
   if (region->regiontype == RGN_TYPE_PREVIEW) {
-    seq = seq_select_seq_from_preview(C, mval, toggle, extend, center);
+    selection.seq1 = seq_select_seq_from_preview(C, mval, toggle, extend, center);

@@ -834,3 +834,3 @@
 }
 
-static bool element_already_selected(const Sequence *seq, const eSeqHandle handle_clicked)
+static bool element_already_selected(StripSelection selection)

@@ -902,0 +944,4 @@
+{
+  seq_rectf(scene, seq, r_body);
+  memcpy(r_left_handle, r_body, sizeof(*r_left_handle));
+  memcpy(r_right_handle, r_body, sizeof(*r_right_handle));

@@ -1101,2 +1309,4 @@
       "Select all strips on same side of the current frame as the mouse cursor");
   RNA_def_property_flag(prop, PROP_SKIP_SAVE);
+
+  /* Used for handle tweaking. */

@@ -54,6 +54,19 @@
 /** \name Selection Utilities
  * \{ */
 
+class MouseCoords {

@@ -56,1 +56,4 @@
 
+class MouseCoords {
+ public:
+  int region[2];

@@ -939,3 +1141,1 @@
-  int mval[2];
-  mval[0] = RNA_int_get(op->ptr, "mouse_x");
-  mval[1] = RNA_int_get(op->ptr, "mouse_y");
+  MouseCoords mouse_co = MouseCoords(

@@ -1107,0 +1334,4 @@
+    return OPERATOR_CANCELLED;
+  }
+
+  MouseCoords mouse_co = MouseCoords(

@@ -1107,0 +1349,4 @@
+    return OPERATOR_CANCELLED;
+  }
+
+  bool changed = false;