diff --git a/core/ui/src/main/java/org/phoebus/ui/docking/DockPane.java b/core/ui/src/main/java/org/phoebus/ui/docking/DockPane.java
index cca55779c..dc642ea17 100644
--- a/core/ui/src/main/java/org/phoebus/ui/docking/DockPane.java
+++ b/core/ui/src/main/java/org/phoebus/ui/docking/DockPane.java
@@ -14,6 +14,7 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.function.Consumer;
 import java.util.logging.Level;
@@ -299,7 +300,7 @@ public void setDockParent(final Parent dock_parent)
         if (dock_parent == null ||
             dock_parent instanceof BorderPane  ||
             dock_parent instanceof SplitDock   ||
-            dock_parent instanceof SplitPane) // "dock_parent instanceof SplitPane" is for the case of the Navigator application running
+            dock_parent instanceof SplitPane) // "dock_parent instanceof SplitPane" is for the case of the ESS-specific Navigator application running
             this.dock_parent = dock_parent;
         else
             throw new IllegalArgumentException("Expected BorderPane or SplitDock or SplitPane, got " + dock_parent);
@@ -654,11 +655,17 @@ else if (dock_parent instanceof BorderPane)
             // Place that new split in the border pane
             parent.setCenter(split);
         }
-        else if (dock_parent instanceof SplitPane)
+        else if (dock_parent instanceof SplitPane) // "dock_parent instanceof SplitPane" is for the case of the ESS-specific Navigator application running
         {
             final SplitPane parent = (SplitPane) dock_parent;
             // Remove this dock pane from BorderPane
-            double dividerPosition = parent.getDividerPositions()[0];
+            Optional<Double> dividerPosition;
+            if (parent.getDividerPositions().length > 1) {
+                dividerPosition = Optional.of(parent.getDividerPositions()[0]);
+            }
+            else {
+                dividerPosition = Optional.empty();
+            }
             parent.getItems().remove(this);
             // Place in split alongside a new dock pane
             final DockPane new_pane = new DockPane();
@@ -668,7 +675,9 @@ else if (dock_parent instanceof SplitPane)
             new_pane.setDockParent(split);
             // Place that new split in the border pane
             parent.getItems().add(split);
-            parent.setDividerPosition(0, dividerPosition);
+            if (dividerPosition.isPresent()) {
+                parent.setDividerPosition(0, dividerPosition.get());
+            }
         }
         else
             throw new IllegalStateException("Cannot split, dock_parent is " + dock_parent);
diff --git a/core/ui/src/main/java/org/phoebus/ui/docking/SplitDock.java b/core/ui/src/main/java/org/phoebus/ui/docking/SplitDock.java
index 357176839..f8482cd41 100644
--- a/core/ui/src/main/java/org/phoebus/ui/docking/SplitDock.java
+++ b/core/ui/src/main/java/org/phoebus/ui/docking/SplitDock.java
@@ -170,11 +170,13 @@ else if (dock_parent instanceof SplitDock)
             final boolean was_first = parent.removeItem(this);
             parent.addItem(was_first, child);
         }
-        else if (dock_parent instanceof SplitPane) {
+        else if (dock_parent instanceof SplitPane) { // "dock_parent instanceof SplitPane" is for the case of the ESS-specific Navigator application running
             final SplitPane parent = (SplitPane) dock_parent;
-            // parent.getItems().get(1) == this, parent.getItems().get(0) == Navigator application
-            // No need to remove 'this' from parent, just update parent.getItems().get(1) to child
-            parent.getItems().set(1, child);
+            // parent.getItems().get(1) == this, parent.getItems().get(0) == (ESS-specific) Navigator application,
+            // when the (ESS-specific) Navigator is being displayed.
+            // parent.getItems().get(0) == this when (ESS-specific) Navigator is not being displayed.
+            // No need to remove 'this' from parent, just update parent.getItems().get(last index) to child
+            parent.getItems().set(parent.getItems().size()-1, child);
         }
         else
         {