Fix alignment of number pad buttons

src/Calculator/Views/CalculatorProgrammerRadixOperators.xaml

@@ -727,7 +727,8 @@
                              Grid.Row="2"
                              Grid.RowSpan="4"
                              Grid.Column="1"
-                             Grid.ColumnSpan="3"
+                             Grid.ColumnSpan="4"
+                             ExtraColumns="1"
                              ButtonStyle="{StaticResource NumericButtonStyle18}"
                              CurrentRadixType="{x:Bind Model.CurrentRadixType, Mode=OneWay}"/>
         </Grid>

src/Calculator/Views/CalculatorScientificOperators.xaml

@@ -1303,7 +1303,8 @@
                          Grid.Row="4"
                          Grid.RowSpan="4"
                          Grid.Column="1"
-                         Grid.ColumnSpan="3"
+                         Grid.ColumnSpan="4"
+                         ExtraColumns="1"
                          AutomationProperties.HeadingLevel="Level1"
                          AutomationProperties.Name="{utils:ResourceString Name=NumberPad/[using:Windows.UI.Xaml.Automation]AutomationProperties/Name}"
                          ButtonStyle="{StaticResource NumericButtonStyle24}"/>

src/Calculator/Views/CalculatorStandardOperators.xaml

@@ -329,7 +329,8 @@
                          Grid.Row="2"
                          Grid.RowSpan="4"
                          Grid.Column="2"
-                         Grid.ColumnSpan="3"
+                         Grid.ColumnSpan="4"
+                         ExtraColumns="1"
                          AutomationProperties.HeadingLevel="Level1"
                          AutomationProperties.Name="{utils:ResourceString Name=NumberPad/[using:Windows.UI.Xaml.Automation]AutomationProperties/Name}"
                          ButtonStyle="{StaticResource NumericButtonStyle24}"/>

src/Calculator/Views/NumberPad.xaml.cs

@@ -1,5 +1,6 @@
 using CalculatorApp.ViewModel.Common;
 
+using System;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 
@@ -29,6 +30,20 @@ public NumberPad()
             Num9Button.Content = localizationSettings.GetDigitSymbolFromEnUsDigit('9');
         }
 
+        // Extra empty columns to the right so that column widths are calculated consistently with the rest of the button panel.
+
+        public int ExtraColumns
+        {
+            get => (int)GetValue(ExtraColumnsProperty);
+            set => SetValue(ExtraColumnsProperty, value);
+        }
+
+        public static readonly DependencyProperty ExtraColumnsProperty =
+            DependencyProperty.Register(nameof(ExtraColumns), typeof(int), typeof(NumberPad), new PropertyMetadata(0, (sender, args) =>
+            {
+                ((NumberPad)sender).OnExtraColumnsPropertyChanged((int)args.OldValue, (int)args.NewValue);
+            }));
+
         public Windows.UI.Xaml.Style ButtonStyle
         {
             get => (Windows.UI.Xaml.Style)GetValue(ButtonStyleProperty);
@@ -67,6 +82,29 @@ public bool IsErrorVisualState
             }
         }
 
+        private void OnExtraColumnsPropertyChanged(int oldValue, int newValue)
+        {
+            if (newValue < 0)
+            {
+                throw new ArgumentException($"ExtraColumns of value {newValue} is smaller than 0.");
+            }
+            var columnDefinitions = Root.ColumnDefinitions;
+            if (newValue > oldValue)
+            {
+                for (int i = oldValue; i < newValue; ++i)
+                {
+                    columnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) });
+                }
+            }
+            else
+            {
+                for (int i = oldValue; i > newValue; --i)
+                {
+                    columnDefinitions.RemoveAt(columnDefinitions.Count - 1);
+                }
+            }
+        }
+
         private void OnCurrentRadixTypePropertyChanged(NumberBase oldValue, NumberBase newValue)
         {
             Num0Button.IsEnabled = true;