DataGrid's selected row color when inactive
Solution 1:
After ages of searching, I found a surprisingly simple way to do this that's cleaner than the Got/LostFocus approach posted earlier:
<DataGrid.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="DarkGray"/>
</DataGrid.Resources>
This just sets the inactive background colour to DarkGray, leaving the active background colour to the default, but you can change that too using the SystemColors.HighlightBrushKey too of course.
The foreground resource key for inactive selections is SystemColors.InactiveSelectionHighlightTextBrushKey.
Solution 2:
Complete solution that works for 4.0. Note that this on the CellStyle.
<DataGrid.CellStyle>
<!--Override Highlighting so that its easy to see what is selected even when the control is not focused-->
<Style TargetType="{x:Type DataGridCell}">
<Style.Triggers>
<Trigger Property="IsSelected" Value="true">
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" />
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}" />
<Setter Property="BorderBrush" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" />
</Trigger>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="True" />
<Condition Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=DataGrid}, Path=IsKeyboardFocusWithin}" Value="False" />
</MultiDataTrigger.Conditions>
<MultiDataTrigger.Setters>
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" />
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}" />
<Setter Property="BorderBrush" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" />
</MultiDataTrigger.Setters>
</MultiDataTrigger>
</Style.Triggers>
</Style>
</DataGrid.CellStyle>
Solution 3:
Do it like this:
<DataGrid ...>
<DataGrid.Resources>
<Style TargetType="DataGridRow">
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Red"/>
</Style.Resources>
</Style>
</DataGrid.Resources>
...
Solution 4:
None of these answers gave me quite what I was looking for. The top rated by Steve Streeting changed other sections of the datagrid that I didn't want to change, and other answers weren't providing the inactive color change, but were properly targeting the row only. So here's a mixture of their answers that changes the inactive color, only on the rows and not in other places on the grid.
<DataGrid.Resources>
<Style TargetType="DataGridRow">
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="DarkGray"/>
</Style.Resources>
</Style>
</DataGrid.Resources>