Index: trunk/src/org/openstreetmap/josm/gui/preferences/plugin/PluginListPanel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/plugin/PluginListPanel.java	(revision 16409)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/plugin/PluginListPanel.java	(revision 16410)
@@ -178,3 +178,13 @@
         SwingUtilities.invokeLater(() -> scrollRectToVisible(visibleRect));
     }
+
+    @Override
+    public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
+        return visibleRect.height / 4;
+    }
+
+    @Override
+    public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
+        return visibleRect.height;
+    }
 }