title: Nullable database property but texbox still shows red border when content deleted
body: <p>Hi I am binding a WPF textbox to an Entity Framework property as follows:</p>
  
  <pre><code>&lt;TextBox Grid.Column="1" Grid.Row="0" Margin="5,2" 
           Text="{Binding Path=MyEntityObject.SizeLower, Mode=TwoWay}" /&gt;
  </code></pre>
  
  <p>It binds fine to the property and when I change it, it saves to the DB as expected. But if I delete the content of the Textbox I get the red error border around it. I dont have any validator in place so I am guessing the texbox is complaining about the value not being nullable. But in fact this property in the DB is nullable, so I cannot understand why it would error.</p>
  
  <p>The system generated EF property definition is as follows:</p>
  
  <pre><code>&lt;EdmScalarPropertyAttribute(EntityKeyProperty:=false, IsNullable:=true)&gt;
  &lt;DataMemberAttribute()&gt;
  Public Property SizeLower() As Nullable(Of Global.System.Int64)
      Get
          Return _SizeLower
      End Get
      Set
          OnSizeLowerChanging(value)
          ReportPropertyChanging("SizeLower")
          _SizeLower = StructuralObject.SetValidValue(value)
          ReportPropertyChanged("SizeLower")
          OnSizeLowerChanged()
      End Set
  End Property
  
  Private _SizeLower As Nullable(Of Global.System.Int64)
  </code></pre>
  
  <p>Is there something I am missing? I thought the binding system was able to determine if a property was nullable and allow nulls if so?</p>
  
  <p>How can I see what the error is? Hovering doesnt seem to do the trick.</p>
  
  <p>Thanks for any advice.</p>
  
  <p>===================================
  ADDITIONAL INFO</p>
  
  <p>If I select all and delete, then change focus, the validation box appears. Here's a screencapture before and after. Also I have confirmed that I can manually put NULLs in the database for the bound properties so thats not the problem.</p>
  
  <p>DENIED. Tried to put picture here but I dont have 10 points...!
  Here is an offsite link instead: <a href="http://ebaypics.net/ProgrammingPics/RedSelectionBox.gif" rel="nofollow">CLICK HERE</a></p>