Index: trunk/src/org/openstreetmap/josm/gui/MainApplication.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/MainApplication.java	(revision 16497)
+++ trunk/src/org/openstreetmap/josm/gui/MainApplication.java	(revision 16498)
@@ -869,4 +869,7 @@
         setupCallbacks();
 
+        // Configure Look and feel before showing SplashScreen (#19290)
+        setupUIManager();
+
         final SplashScreen splash = GuiHelper.runInEDTAndWaitAndReturn(SplashScreen::new);
         // splash can be null sometimes on Linux, in this case try to load JOSM silently
@@ -903,5 +906,4 @@
 
         monitor.indeterminateSubTask(tr("Setting defaults"));
-        setupUIManager();
         toolbar = new ToolbarPreferences();
         ProjectionPreference.setProjection();