Updated ordering and documentation

Author: georgweiss

app/save-and-restore/app/doc/index.rst

@@ -303,6 +303,29 @@ are shown by default. The left-most columns in the toolbar can be used to show/h
 .. image:: images/toggle-readback.png
    :width: 80%
 
+While comparison of scalar values in the snapshot view is straight-forward, array (or table) type data is difficult
+to compare from the single table cells. User may instead click on the highlighted ":math:`{\Delta}` Live" cell to launch a dialog
+showing stored, live and :math:`{\Delta}` for the selected PV:
+
+.. image:: images/snapshot-view-with-delta.png
+
+User clicks "Click to compare":
+
+.. image:: images/compare-arrays.png
+
+The threshold settings works in the same manner is in the snapshot view and operates on each element (row) in the
+table view.
+
+In case the stored and live value of the array/table data are of different dimensions, cells where no value is available
+will be rendered as "---". Moreover, since in these cases an absolute delta cannot be computed, the delta column will also show
+"---".
+
+User may click the table header of the delta column to sort on the delta value to quickly find rows where either the
+stored or live value is not defined (due to difference in dimension). For such rows the absolute delta will be treated
+as infinite, which impacts ordering on the delta column:
+
+.. image:: images/compare-arrays-infinite-delta.png
+
 Restoring A Snapshot
 --------------------
 

app/save-and-restore/app/src/test/java/org/phoebus/applications/saveandrestore/ui/snapshot/compare/ComparisonDialogDemo.java

@@ -30,7 +30,7 @@ public void start(Stage primaryStage) {
                         Alarm.none(),
                         Time.now(), Display.none());
         ComparisonDialog comparisonDialog =
-                new ComparisonDialog(vDoubleArray, "loc://x(3, 2, 1)");
+                new ComparisonDialog(vDoubleArray, "loc://x(3, 2, 1, 1)");
         comparisonDialog.show();
     }
 }