WPF DataGrid HeaderTemplate Mysterious Fill

Question

I put one button with an image in the header of the DataGrid column. The cell template is also just a simple button with an image.

<my:DataGridTemplateColumn>
    <my:DataGridTemplateColumn.HeaderTemplate>
        <DataTemplate>
            <Button ToolTip="Add New Template" Name="AddNewTemplate" Click="AddNewTemplate_Click">
                <Image Source="../Resources/add.png"/>
            </Button>
        </DataTemplate>
    </my:DataGridTemplateColumn.HeaderTemplate>
    <my:DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <Button ToolTip="Edit Template" Name="EditTemplate" Click="EditTemplate_Click" Tag="{Binding}">
                <Image Source="../Resources/pencil.png"/>
            </Button>
        </DataTemplate>
   </my:DataGridTemplateColumn.CellTemplate>
</my:DataGridTemplateColumn>

When rendering, the header has approximately 10-15px indentation only on the right side, which forces the cells to obviously display at this width, leaving the cell button with blank space on both sides. Being a pixel perfectionist, it annoys me. Initially, I thought it was a space for arrows displayed during sorting, but I have disabled sorting both across the entire DataGrid and explicitly in the column.

Here is the image: http://img716.imageshack.us/img716/1787/68487749.png

, . - ?

---

:

• http://img704.imageshack.us/i/23206794.png/
• http://img229.imageshack.us/i/65917762.png/

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:

<my:DataGrid.Resources>
    <Style x:Key="addHeader" TargetType="{x:Type myp:DataGridColumnHeader}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type myp:DataGridColumnHeader}">
                    <Button ToolTip="Add New Template" Name="AddNewTemplate" Click="AddNewTemplate_Click" Margin="4">
                        <Image Source="../Resources/add.png"/>
                    </Button>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</my:DataGrid.Resources>
<my:DataGrid.Columns>
    <my:DataGridTemplateColumn HeaderStyle="{StaticResource addHeader}">
        <my:DataGridTemplateColumn.CellTemplate>
            <DataTemplate>
                <Button ToolTip="Edit Template" Name="EditTemplate" Click="EditTemplate_Click" Tag="{Binding}">
                    <Image Source="../Resources/pencil.png"/>
                </Button>
            </DataTemplate>
        </my:DataGridTemplateColumn.CellTemplate>
    </my:DataGridTemplateColumn>
</my:DataGrid.Columns>

Answer 1

Snoop !

, , DataGridHeaderBorder.cs:

   protected override Size ArrangeOverride(Size arrangeSize)
   {
     //...
     if (padding.Equals(new Thickness()))
     {
       padding = DefaultPadding;
     }
     //...
     child.Arrange(new Rect(padding.Left, padding.Top, childWidth, childHeight));
   }

DefaultPadding 0... , .

? , . . . .

Answer 2

Padding = "0,0.000001,0,0", , ( , .NET 4.0).