Index: /trunk/src/org/openstreetmap/josm/actions/ViewportFollowToggleAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/actions/ViewportFollowToggleAction.java	(revision 17794)
+++ /trunk/src/org/openstreetmap/josm/actions/ViewportFollowToggleAction.java	(revision 17795)
@@ -43,4 +43,8 @@
     @Override
     public void actionPerformed(ActionEvent e) {
+        if (!ExpertToggleAction.isExpert()) {
+            // #16848 (Possible to activate "Viewport following" mode when not in "Expert mode" through keyboard shortcut)
+            return;
+        }
         toggleSelectedState(e);
         DrawAction.VIEWPORT_FOLLOWING.put(isSelected());