Index: src/org/openstreetmap/josm/gui/download/OSMDownloadSource.java
===================================================================
--- src/org/openstreetmap/josm/gui/download/OSMDownloadSource.java	(revision 18701)
+++ src/org/openstreetmap/josm/gui/download/OSMDownloadSource.java	(working copy)
@@ -211,8 +211,10 @@
             setLayout(new GridBagLayout());
 
             // size check depends on selected data source
-            checkboxChangeListener = e ->
-                    dialog.getSelectedDownloadArea().ifPresent(this::updateSizeCheck);
+            checkboxChangeListener = e -> {
+                rememberSettings();
+                dialog.getSelectedDownloadArea().ifPresent(OSMDownloadSourcePanel.this::boundingBoxChanged);
+            };
 
             downloadSourcesPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
             add(downloadSourcesPanel, GBC.eol().fill(GBC.HORIZONTAL));
@@ -324,15 +326,6 @@
 
         @Override
         public void boundingBoxChanged(Bounds bbox) {
-            updateSizeCheck(bbox);
-        }
-
-        @Override
-        public String getSimpleName() {
-            return SIMPLE_NAME;
-        }
-
-        private void updateSizeCheck(Bounds bbox) {
             if (bbox == null) {
                 sizeCheck.setText(tr("No area selected yet"));
                 sizeCheck.setForeground(Color.darkGray);
@@ -340,9 +333,15 @@
             }
 
             displaySizeCheckResult(DOWNLOAD_SOURCES.stream()
+                    .filter(IDownloadSourceType::isEnabled)
                     .anyMatch(type -> type.isDownloadAreaTooLarge(bbox)));
         }
 
+        @Override
+        public String getSimpleName() {
+            return SIMPLE_NAME;
+        }
+
         private void displaySizeCheckResult(boolean isAreaTooLarge) {
             if (isAreaTooLarge) {
                 sizeCheck.setText(tr("Download area too large; will probably be rejected by server"));
@@ -414,7 +413,7 @@
         @Override
         public boolean isDownloadAreaTooLarge(Bounds bound) {
             // see max_request_area in
-            // https://github.com/openstreetmap/openstreetmap-website/blob/master/config/example.application.yml
+            // https://github.com/openstreetmap/openstreetmap-website/blob/master/config/settings.yml
             return bound.getArea() > Config.getPref().getDouble("osm-server.max-request-area", 0.25);
         }
     }
@@ -492,7 +491,7 @@
         @Override
         public boolean isDownloadAreaTooLarge(Bounds bound) {
             // see max_note_request_area in
-            // https://github.com/openstreetmap/openstreetmap-website/blob/master/config/example.application.yml
+            // https://github.com/openstreetmap/openstreetmap-website/blob/master/config/settings.yml
             return bound.getArea() > Config.getPref().getDouble("osm-server.max-request-area-notes", 25);
         }
     }