Tweaks to Resize Arrange By correctly and use NSPopUpButton instead of NSComboBox for constrained predefined values.

Xamarin.PropertyEditing.Mac.Standalone/Main.storyboard

@@ -672,7 +672,7 @@
         <scene sceneID="hIz-AP-VOD">
             <objects>
                 <viewController id="XfG-lQ-9wD" customClass="ViewController" sceneMemberID="viewController">
-                    <view key="view" id="m2S-Jp-Qdl">
+                    <view key="view" id="m2S-Jp-Qdl" wantsLayer="YES">
                         <rect key="frame" x="0.0" y="0.0" width="480" height="270"/>
                         <autoresizingMask key="autoresizingMask"/>
                         <subviews>

Xamarin.PropertyEditing.Mac/Controls/PredefinedValuesEditor.cs

@@ -19,35 +19,51 @@ namespace Xamarin.PropertyEditing.Mac
 		{
 			base.TranslatesAutoresizingMaskIntoConstraints = false;
 
-			this.comboBox = new NSComboBox () {
+			this.comboBox = new NSComboBox {
 				TranslatesAutoresizingMaskIntoConstraints = false,
 				BackgroundColor = NSColor.Clear,
 				StringValue = String.Empty,
 				Cell = {
-					ControlSize = NSControlSize.Regular
+					ControlSize = NSControlSize.Small
 				},
 				Editable = false,
 			};
 
+			this.popUpButton = new NSPopUpButton {
+				TranslatesAutoresizingMaskIntoConstraints = false,
+				StringValue = String.Empty,
+				Cell = {
+					ControlSize = NSControlSize.Small
+				},
+			};
+
 			this.comboBox.SelectionChanged += (sender, e) => {
 				EditorViewModel.ValueName = comboBox.SelectedValue.ToString ();
 			};
 
-			AddSubview (this.comboBox);
+			popupButtonList = new NSMenu ();
+			popUpButton.Menu = popupButtonList;
 
-			this.DoConstraints (new[] {
-				comboBox.ConstraintTo (this, (cb, c) => cb.Width == c.Width - 28),
-				comboBox.ConstraintTo (this, (cb, c) => cb.Left == c.Left + 3),
-			});
+			popUpButton.Activated += (o, e) => {
+				EditorViewModel.ValueName = (o as NSPopUpButton).Title;
+			};
 
 			UpdateTheme ();
 		}
 
-		public override NSView FirstKeyView => this.comboBox;
-		public override NSView LastKeyView => this.comboBox;
+		public override NSView FirstKeyView => firstKeyView;
+		public override NSView LastKeyView => lastKeyView;
 
 		protected PredefinedValuesViewModel<T> EditorViewModel => (PredefinedValuesViewModel<T>)ViewModel;
 
+		readonly NSComboBox comboBox;
+		readonly NSPopUpButton popUpButton;
+		NSMenu popupButtonList;
+
+		bool dataPopulated;
+		NSView firstKeyView;
+		NSView lastKeyView;
+
 		protected override void HandleErrorsChanged (object sender, DataErrorsChangedEventArgs e)
 		{
 			UpdateErrorsDisplayed (ViewModel.GetErrors (e.PropertyName));
@@ -55,7 +71,11 @@ namespace Xamarin.PropertyEditing.Mac
 
 		protected override void SetEnabled ()
 		{
-			this.comboBox.Editable = ViewModel.Property.CanWrite;
+			if (EditorViewModel.IsConstrainedToPredefined) {
+				this.popUpButton.Enabled = ViewModel.Property.CanWrite;
+			} else {
+				this.comboBox.Enabled = ViewModel.Property.CanWrite;
+			}
 		}
 
 		protected override void UpdateErrorsDisplayed (IEnumerable errors)
@@ -70,9 +90,44 @@ namespace Xamarin.PropertyEditing.Mac
 
 		protected override void OnViewModelChanged (PropertyViewModel oldModel)
 		{
-			this.comboBox.RemoveAll ();
-			foreach (string item in EditorViewModel.PossibleValues) {
-				this.comboBox.Add (new NSString (item));
+			if (!dataPopulated) {
+				if (EditorViewModel.IsConstrainedToPredefined) {
+					this.popupButtonList.RemoveAllItems ();
+					foreach (string item in EditorViewModel.PossibleValues) {
+						popupButtonList.AddItem (new NSMenuItem (item));
+					}
+
+					AddSubview (this.popUpButton);
+
+					this.DoConstraints (new[] {
+						popUpButton.ConstraintTo (this, (pub, c) => pub.Width == c.Width - 26),
+						popUpButton.ConstraintTo (this, (pub, c) => pub.Left == c.Left + 3),
+						popUpButton.ConstraintTo (this, (pub, c) => pub.Top == c.Top + 6),
+					});
+
+					firstKeyView = this.popUpButton;
+					lastKeyView = this.popUpButton;
+				} else {
+					this.comboBox.RemoveAll ();
+
+					// Once the VM is loaded we need a one time population
+					foreach (var item in EditorViewModel.PossibleValues) {
+						this.comboBox.Add (new NSString (item));
+					}
+
+					AddSubview (this.comboBox);
+
+					this.DoConstraints (new[] {
+						comboBox.ConstraintTo (this, (cb, c) => cb.Width == c.Width - 28),
+						comboBox.ConstraintTo (this, (cb, c) => cb.Left == c.Left + 3),
+						comboBox.ConstraintTo (this, (cb, c) => cb.Top == c.Top + 4),
+					});
+
+					firstKeyView = this.comboBox;
+					lastKeyView = this.comboBox;
+				}
+
+				dataPopulated = true;
 			}
 
 			base.OnViewModelChanged (oldModel);
@@ -80,15 +135,22 @@ namespace Xamarin.PropertyEditing.Mac
 
 		protected override void UpdateValue ()
 		{
-			this.comboBox.StringValue = EditorViewModel.ValueName ?? String.Empty;
+			if (EditorViewModel.IsConstrainedToPredefined) {
+				this.popUpButton.Title = EditorViewModel.ValueName ?? String.Empty;
+			} else {
+				this.comboBox.StringValue = EditorViewModel.ValueName ?? String.Empty;
+			}
 		}
 
-		private readonly NSComboBox comboBox;
-
 		protected override void UpdateAccessibilityValues ()
 		{
-			comboBox.AccessibilityEnabled = comboBox.Enabled;
-			comboBox.AccessibilityTitle = Strings.AccessibilityCombobox (ViewModel.Property.Name);
+			if (EditorViewModel.IsConstrainedToPredefined) {
+				popUpButton.AccessibilityEnabled = popUpButton.Enabled;
+				popUpButton.AccessibilityTitle = Strings.AccessibilityCombobox (ViewModel.Property.Name);
+			} else {
+				comboBox.AccessibilityEnabled = comboBox.Enabled;
+				comboBox.AccessibilityTitle = Strings.AccessibilityCombobox (ViewModel.Property.Name);
+			}
 		}
 	}
 }

Xamarin.PropertyEditing.Mac/PropertyEditorPanel.cs

@@ -166,11 +166,11 @@ namespace Xamarin.PropertyEditing.Mac
 				propertyFilter.ConstraintTo(this, (pf, c) => pf.Left == c.Left + 12),
 
 				propertyArrangeModeLabel.ConstraintTo(this, (pl, c) => pl.Top == c.Top + 5),
-				propertyArrangeModeLabel.ConstraintTo(propertyArrangeMode, (pl, pa) => pl.Left == pa.Left - 73),
+				propertyArrangeModeLabel.ConstraintTo(propertyArrangeMode, (pl, pa) => pl.Left == pa.Left - 71),
 
 				propertyArrangeMode.ConstraintTo(this, (pa, c) => pa.Top == c.Top + 3),
-				propertyArrangeMode.ConstraintTo(this, (pa, c) => pa.Left == c.Left + 312),
-				propertyArrangeMode.ConstraintTo(this, (pa, c) => pa.Width == 154),
+				propertyArrangeMode.ConstraintTo(this, (pa, c) => pa.Left == c.Left + 310),
+				propertyArrangeMode.ConstraintTo(this, (pa, c) => pa.Width == c.Width - 320),
 
 				tableContainer.ConstraintTo(this, (t, c) => t.Top == c.Top + 30),
 				tableContainer.ConstraintTo(this, (t, c) => t.Width == c.Width - 20),

Xamarin.PropertyEditing/ViewModels/PredefinedValuesViewModel.cs

@@ -48,6 +48,8 @@ namespace Xamarin.PropertyEditing.ViewModels
 			}
 		}
 
+		public bool IsConstrainedToPredefined => this.predefinedValues.IsConstrainedToPredefined;
+
 		// TODO: Combination (flags) values
 
 		protected override TValue ValidateValue (TValue validationValue)