Index: src/org/openstreetmap/josm/actions/SimplifyWayAction.java
===================================================================
--- src/org/openstreetmap/josm/actions/SimplifyWayAction.java	(revision 18904)
+++ src/org/openstreetmap/josm/actions/SimplifyWayAction.java	(working copy)
@@ -64,6 +64,10 @@
  */
 public class SimplifyWayAction extends JosmAction {
 
+    private static final String previewPreference = "simplifyWay.preview";
+
+    private static JCheckBox preview;
+
     /**
      * Constructs a new {@code SimplifyWayAction}.
      */
@@ -198,6 +202,19 @@
 
         q.setBorder(BorderFactory.createEmptyBorder(14, 0, 10, 0));
         p.add(q, GBC.eol());
+        preview = new JCheckBox(tr("Preview"), true);
+        Config.getPref().putBoolean(previewPreference, preview.isSelected());
+        preview.addActionListener(
+                actionEvent -> {
+                    boolean isSelected = preview.isSelected();
+                    Config.getPref().putBoolean(previewPreference, isSelected);
+                    if (isSelected) {
+                        l.stateChanged(null);
+                    } else {
+                        changeCleanup.run();
+                    }
+                });
+        p.add(preview, GBC.eol());
         JCheckBox c = new JCheckBox(tr("Do not ask again"));
         p.add(c, GBC.eol());
 
@@ -535,6 +552,9 @@
 
         @Override
         public void stateChanged(ChangeEvent e) {
+            if (preview != null) {
+                preview.setSelected(true);
+            }
             if (Objects.equals(UndoRedoHandler.getInstance().getLastCommand(), lastCommand)) {
                 UndoRedoHandler.getInstance().undo();
             }