Fixed some minor ui things with constraints

XSDVisualiser.Desktop/Converters/CollectionHasItemsConverter.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections;
+using System.Globalization;
+using Avalonia.Data.Converters;
+
+namespace XSDVisualiser.Desktop.Converters
+{
+    /// <summary>
+    /// Returns true if the bound value is a collection with at least one item. Supports IEnumerable and ICollection.
+    /// Optional parameter "Invert" to invert the boolean result.
+    /// </summary>
+    public sealed class CollectionHasItemsConverter : IValueConverter
+    {
+        public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        {
+            var hasItems = false;
+            switch (value)
+            {
+                case ICollection coll:
+                    hasItems = coll.Count > 0;
+                    break;
+                case IEnumerable enumerable:
+                {
+                    var enumerator = enumerable.GetEnumerator();
+                    hasItems = enumerator.MoveNext();
+                    break;
+                }
+            }
+
+            var invert = parameter is string s && s.Equals("Invert", StringComparison.OrdinalIgnoreCase);
+            return invert ? !hasItems : hasItems;
+        }
+
+        public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+            => throw new NotSupportedException();
+    }
+}

XSDVisualiser.Desktop/MainWindow.axaml

@@ -9,6 +9,7 @@
         <conv:CardinalityToLabelConverter x:Key="CardinalityToLabel"/>
         <conv:OptionalToBorderBrushConverter x:Key="OptionalToBrush"/>
         <conv:OptionalToThicknessConverter x:Key="OptionalToThickness"/>
+        <conv:CollectionHasItemsConverter x:Key="HasItems"/>
     </Window.Resources>
 
     <Grid RowDefinitions="Auto,*" Margin="12">
@@ -129,7 +130,7 @@
 
                                                         <StackPanel>
                                                             <TextBlock Text="Enumerations" FontWeight="SemiBold"/>
-                                                            <ItemsControl ItemsSource="{Binding Enumerations}">
+                                                            <ItemsControl ItemsSource="{Binding Enumerations}" IsVisible="{Binding Enumerations, Converter={StaticResource HasItems}}">
                                                                 <ItemsControl.ItemTemplate>
                                                                     <DataTemplate x:DataType="x:String">
                                                                         <TextBlock Text="{Binding ., StringFormat=• {0}}"/>
@@ -140,7 +141,7 @@
 
                                                         <StackPanel>
                                                             <TextBlock Text="Patterns" FontWeight="SemiBold"/>
-                                                            <ItemsControl ItemsSource="{Binding Patterns}">
+                                                            <ItemsControl ItemsSource="{Binding Patterns}" IsVisible="{Binding Patterns, Converter={StaticResource HasItems}}">
                                                                 <ItemsControl.ItemTemplate>
                                                                     <DataTemplate x:DataType="x:String">
                                                                         <TextBlock Text="{Binding ., StringFormat=• {0}}"/>