Merge pull request 'B2025-019 RO Editor - When selecting an RO Definition, clicking the X in the corner or selecting Cancel prompts you to verify you want to close without saving changes when no changes were made if there is Parent/Child & applicability was never set for …' (#521) from B2025-019 into Development

good for testing phase (remember to build the Reference Objects project)

PROMS/ReferencedObjects/Exe/RefObj/ROEditor/RODefFrm.cs

@@ -1584,7 +1584,7 @@ namespace ROEditor
 					if (i + 1 < InUseList.Count) inuserecs = inuserecs + " ";
 				}
 			}
-			if (inuserecs != origFieldsInUse)
+			if ((inuserecs ?? "") != (origFieldsInUse ?? ""))
 				return true;
 
 
@@ -1599,7 +1599,7 @@ namespace ROEditor
 					if (i + 1 < InUseApplcList.Count) applicfieldrecs = applicfieldrecs + " ";
 				}
 			}
-			if (applicfieldrecs != origApplicFields)
+			if ((applicfieldrecs ?? "") != (origApplicFields ?? ""))
 				return true;
 
 			//nothing has changed