LT-22373c: Fix NumberingStyle get in DictionaryNodeOptions

Src/xWorks/DictionaryConfigurationController.cs

@@ -520,18 +520,18 @@ public static void SetConfigureHomographParameters(DictionaryConfigurationModel
 			var senseNode = mainEntryNode.Children.Where(prop => prop.Label == senseType).FirstOrDefault();
 			if (senseNode == null) return;
 			var senseOptions = (DictionaryNodeSenseOptions)senseNode.DictionaryNodeOptions;
-			cacheHc.ksSenseNumberStyle = senseOptions.NumberingStyle;
+			cacheHc.ksSenseNumberStyle = senseOptions.NonEmptyNumberingStyle;
 			//SubSense Node
 			var subSenseNode = senseNode.Children.Where(prop => prop.Label == "Subsenses").FirstOrDefault();
 			if (subSenseNode == null) return;
 			var subSenseOptions = (DictionaryNodeSenseOptions)subSenseNode.DictionaryNodeOptions;
-			cacheHc.ksSubSenseNumberStyle = subSenseOptions.NumberingStyle;
+			cacheHc.ksSubSenseNumberStyle = subSenseOptions.NonEmptyNumberingStyle;
 			cacheHc.ksParentSenseNumberStyle = subSenseOptions.ParentSenseNumberingStyle;
 			//SubSubSense Node
 			var subSubSenseNode = subSenseNode.ReferencedOrDirectChildren.Where(prop => prop.Label == "Subsenses").FirstOrDefault();
 			if (subSubSenseNode == null) return;
 			var subSubSenseOptions = (DictionaryNodeSenseOptions)subSubSenseNode.DictionaryNodeOptions;
-			cacheHc.ksSubSubSenseNumberStyle = subSubSenseOptions.NumberingStyle;
+			cacheHc.ksSubSubSenseNumberStyle = subSubSenseOptions.NonEmptyNumberingStyle;
 			cacheHc.ksParentSubSenseNumberStyle = subSubSenseOptions.ParentSenseNumberingStyle;
 		}
 

Src/xWorks/DictionaryDetailsView/SenseOptionsView.cs

@@ -66,8 +66,12 @@ public string NumberingStyle
 		{
 			get
 			{
-				// Return null if string is empty, because returning an empty string for reversal numbers
-				// also forces sense numbers not to be displayed. Null doesn't cause the same problem.
+				// Handles NumberingStyle for the dictionary/reversal configuration dialog preview display.
+				// Both empty string and null mean there is no numbering style to use.
+				// Numbering style will be null if no numbering style has ever been selected.
+				// Numbering style will be an empty string if a numbering style was selected at some point and then turned back off.
+				// Returning an empty string for reversal numbering style forces sense numbers to be turned off too, but null doesn't cause this problem.
+				// Return null if numbering style is empty.
 				var formatString = ((NumberingStyleComboItem)dropDownNumberingStyle.SelectedItem).FormatString;
 				return string.IsNullOrEmpty(formatString) ? null : formatString;
 			}

Src/xWorks/DictionaryNodeOptions.cs

@@ -56,7 +56,33 @@ public class DictionaryNodeSenseOptions : DictionaryNodeOptions
 
 		// Example values: ""->none; %O->1.2.3; %d->1, 2, 3
 		[XmlAttribute(AttributeName = "numberingStyle")]
-		public string NumberingStyle { get; set; }
+		private string m_NumberingStyle;
+
+		/// <summary>
+		/// Numbering style for senses. If null or empty, no style is used.
+		///
+		/// NumberingStyle is null if no numbering style has ever been selected.
+		/// NumberingStyle is an empty string if a numbering style is selected but then removed.
+		/// </summary>
+		public string NumberingStyle
+		{
+			get => m_NumberingStyle;
+			set => m_NumberingStyle = value;
+		}
+
+		/// <summary>
+		/// Returns the numbering style, or null if no numbering style should be used.
+		///
+		/// <see cref="NumberingStyle"/> may contain either null or an empty string to indicate
+		/// that numbering is disabled. An empty string used for reversals' NumberingStyle also
+		/// forces sense numbers to be disabled. This property normalizes both values to null
+		/// to retain the expected behavior for senses.
+		/// </summary>
+		public string NonEmptyNumberingStyle
+		{
+			get => string.IsNullOrEmpty(m_NumberingStyle) ? null : m_NumberingStyle;
+			set => m_NumberingStyle = value;
+		}
 
 		// Example values: ""->none; %j->Joined; %.->Separated by dot
 		[XmlAttribute(AttributeName = "parentSenseNumberingStyle")]