add style and demo

src/Shared/HandyControl_Shared/Themes/Styles/Base/DatePickerBaseStyle.xaml

@@ -1,7 +1,6 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     xmlns:controls="clr-namespace:HandyControl.Controls"
-                    xmlns:system="clr-namespace:System;assembly=mscorlib"
                     xmlns:interactivity="clr-namespace:HandyControl.Interactivity">
 
     <ResourceDictionary.MergedDictionaries>
@@ -183,13 +182,13 @@
     </ControlTemplate>
 
     <Style x:Key="DatePickerExtendBaseStyle" BasedOn="{StaticResource DatePickerBaseStyle}" TargetType="DatePicker">
-        <Setter Property="Height" Value="{x:Static system:Double.NaN}"/>
+        <Setter Property="Height" Value="Auto"/>
         <Setter Property="controls:InfoElement.Symbol" Value="●"/>
         <Setter Property="Template" Value="{StaticResource DatePickerExtendTopTemplate}"/>
         <Style.Triggers>
             <Trigger Property="controls:InfoElement.TitleAlignment" Value="Left">
                 <Setter Property="Template" Value="{StaticResource DatePickerExtendLeftTemplate}"/>
-                <Setter Property="Width" Value="{x:Static system:Double.NaN}"/>
+                <Setter Property="Width" Value="Auto"/>
             </Trigger>
         </Style.Triggers>
     </Style>
@@ -351,7 +350,7 @@
         <Style.Triggers>
             <Trigger Property="controls:InfoElement.TitleAlignment" Value="Left">
                 <Setter Property="Template" Value="{StaticResource DatePickerPlusLeftTemplate}"/>
-                <Setter Property="Width" Value="{x:Static system:Double.NaN}"/>
+                <Setter Property="Width" Value="Auto"/>
             </Trigger>
         </Style.Triggers>
     </Style>