My fellow geek Jacob Reimers found out that it was a bug in the DataGridCheckBoxColumn’s implementation. Instead of seeking for a Style in the resources, the DataGridCheckBoxColumn creates a new one from scratch and assign it to the CheckBox if you don’t set the ElementStyle property. When the columns are auto-generated, the ElementStyle can’t be set and you have no choice than to have this default style. When you don’t auto-generate the columns, you can set your own custom style and override the default one (happy us !).

A work-around exists(ourah !)

Jacob told me: “why don’t you register to the DataGrid’s AutoGeneratingColumn event and set the ElementStyle there ?“. That’s actually a great idea and it works like a charm. Here is the snippet which performs it:

[csharp]
void grid_AutoGeneratingColumn(object sender,
DataGridAutoGeneratingColumnEventArgs e)
{
if(e.Column is DataGridCheckBoxColumn)
{
var checkBoxColumn = e.Column as DataGridCheckBoxColumn;
var resource = Application.Current.FindResource(typeof(CheckBox));
checkBoxColumn.ElementStyle = resource as Style;
}
}
[/csharp]

As I was porting the Jetpack Theme to WPF I thought it was a little embarrasing to force the users to handle an event just to fix this – little – bug.

So I came up with this enhanced solution in two parts:

As you are now experts with attached properties, I let you discover the code directly on Codeplex.

On the other hand, here is the default Style setter I use for the DataGrid:
[xml]<Style TargetType="{x:Type DataGrid}">
<Setter Property="helpers:DataGridCheckBoxColumnFixer.Fix" Value="True" />
</Style>[/xml]

If you can reproduce this bug, share it on Connect too ! The WPF team have done a great job with this control and this is just a little tiny bug and I hope this will be corrected in the vNext…

Regards.