More cleanup and fixes

Application/Style.xaml

@@ -1,11 +1,30 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
     <Style TargetType="{x:Type TextBox}">
+        <Setter Property="Validation.ErrorTemplate">
+            <Setter.Value>
+                <ControlTemplate>
+                    <StackPanel Orientation="Horizontal">
+                        <AdornedElementPlaceholder x:Name="placeholder" />
+                        <TextBlock FontSize="14"
+                                   Margin="2,0"
+                                   Foreground="White"
+                                   Background="Red"
+                                   TextAlignment="Center"
+                                   Width="16"
+                                   Text="!"
+                                   ToolTip="{Binding AdornedElement.(Validation.Errors)[0].ErrorContent, ElementName=placeholder}" />
+                    </StackPanel>
+                </ControlTemplate>
+            </Setter.Value>
+        </Setter>
         <Style.Triggers>
             <Trigger Property="Validation.HasError"
                      Value="true">
                 <Setter Property="ToolTip"
                         Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" />
+                <Setter Property="Margin"
+                        Value="0,0,18,0" />
             </Trigger>
         </Style.Triggers>
     </Style>