MeasureToolbar: modify ArgumentException message (#539)

* fix typo, remove redundant usings

* Update Toolkit.Samples.UWP_TemporaryKey.pfx

* Update Toolkit.Samples.UWP.csproj

* correct PropertyChangedCallback

src/Samples/Toolkit.SampleApp.UWP/Toolkit.Samples.UWP.csproj

@@ -18,7 +18,7 @@
     <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <WindowsXamlEnableOverview>true</WindowsXamlEnableOverview>
     <PackageCertificateKeyFile>Toolkit.Samples.UWP_TemporaryKey.pfx</PackageCertificateKeyFile>
-    <PackageCertificateThumbprint>B2DB53E5289B8F6A6F775C370DC8E0BF9BC39BA9</PackageCertificateThumbprint>
+    <PackageCertificateThumbprint>27DB1585993252FC4A866B07D20B377D98D3A397</PackageCertificateThumbprint>
     <AppxPackageSigningEnabled>True</AppxPackageSigningEnabled>
     <SuppressXamlWarnings>1500</SuppressXamlWarnings>
     <NoWarn>$(NoWarn);2008;APPX4001</NoWarn>

src/Toolkit/Toolkit.UI.Controls/MeasureToolbar/MeasureToolbar.cs

@@ -15,16 +15,10 @@
 //  ******************************************************************************/
 
 #if WPF || WINDOWS_XAML
-using System;
-using System.Collections.Generic;
 using System.Collections.ObjectModel;
-using System.Drawing;
-using System.Linq;
-using System.Threading.Tasks;
 using Esri.ArcGISRuntime.Data;
 using Esri.ArcGISRuntime.Geometry;
 using Esri.ArcGISRuntime.UI;
-using Esri.ArcGISRuntime.UI.Controls;
 #if WPF
 using System.Windows.Controls.Primitives;
 #endif
@@ -619,7 +613,7 @@ private static void OnLineSketchEditorPropertyChanged(DependencyObject d, Depend
         }
 
         /// <summary>
-        /// Gets or sets the sketch edtiro used for measuring areas.
+        /// Gets or sets the sketch editor used for measuring areas.
         /// </summary>
         public SketchEditor? AreaSketchEditor
         {
@@ -631,7 +625,7 @@ public SketchEditor? AreaSketchEditor
         /// Identifies the <see cref="AreaSketchEditor"/> dependency property.
         /// </summary>
         public static readonly DependencyProperty AreaSketchEditorProperty =
-            DependencyProperty.Register(nameof(AreaSketchEditor), typeof(SketchEditor), typeof(MeasureToolbar), new PropertyMetadata(null, OnLineSketchEditorPropertyChanged));
+            DependencyProperty.Register(nameof(AreaSketchEditor), typeof(SketchEditor), typeof(MeasureToolbar), new PropertyMetadata(null, OnAreaSketchEditorPropertyChanged));
 
         private static void OnAreaSketchEditorPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
         {