fixed IllegalComponentStateException when invoker is not showing in SubMenuUsabilityHelper (issue #692)

CHANGELOG.md

@@ -1,6 +1,14 @@
 FlatLaf Change Log
 ==================
 
+## 3.2-SNAPSHOT
+
+#### Fixed bugs
+
+- Fixed `IllegalComponentStateException` when invoker is not showing in
+  `SubMenuUsabilityHelper`. (issue #692)
+
+
 ## 3.1.1
 
 - IntelliJ Themes:

flatlaf-core/src/main/java/com/formdev/flatlaf/SubMenuUsabilityHelper.java

@@ -153,7 +153,7 @@ debug*/
 
 		// get invoker screen bounds
 		Component invoker = popup.getInvoker();
-		invokerBounds = (invoker != null)
+		invokerBounds = (invoker != null && invoker.isShowing())
 			? new Rectangle( invoker.getLocationOnScreen(), invoker.getSize() )
 			: null;