Index: applications/editors/josm/plugins/merge-overlap/src/mergeoverlap/MyCombinePrimitiveResolverDialog.java
===================================================================
--- applications/editors/josm/plugins/merge-overlap/src/mergeoverlap/MyCombinePrimitiveResolverDialog.java	(revision 27852)
+++ applications/editors/josm/plugins/merge-overlap/src/mergeoverlap/MyCombinePrimitiveResolverDialog.java	(revision 29644)
@@ -377,5 +377,5 @@
             setCancelled(false);
             btnApply.requestFocusInWindow();
-        } else {
+        } else if (isShowing()) { // Avoid IllegalComponentStateException like in #8775
             new WindowGeometry(this).remember(getClass().getName() + ".geometry");
         }