Date: 2019-02-02
Slip (total length not change):
                                   drag left       drag right
                                      <               <                 
+-------------+                  +-------------+ +-------------+
+abc|12345|ABC+ ---------------> +abc|01234|ABC+ +abc|23456|ABC+
+-------------+                  +-------------+ +-------------+
                                          >               >                 
+-------------+                  +-------------+ +-------------+
+abc|12345|ABC+ ---------------> +abc|01234|ABC+ +abc|23456|ABC+
+-------------+                  +-------------+ +-------------+
                                    >               >                 
+-------------+                  +-------------+ +-------------+
+abc|12345|ABC+ ---------------> +zab|12345|ABC+ +bcd|12345|ABC+
+-------------+                  +-------------+ +-------------+
                                            <               <
+-------------+                  +-------------+ +-------------+
+abc|12345|ABC+ ---------------> +abc|12345|ZAB+ +abc|12345|BCD+
+-------------+                  +-------------+ +-------------+

Note 1:
It works so in Cin5.1_20181231 and version before.

Note 2:
It would be useful if the Compositor could show the split view with:
- the view on the left side shows the clip's InPoint that changes;
- the view on the right side shows the clips's OutPoint that changes.