XAML change button background if databinding value is true - wpf

Question

I'm trying to change the background of a button, if a property of the data binding is true.
To give a short overview - I have a ListBox. I also gave this ListBox a style for the items:
<ListBox Margin="0,5,0,0" Background="Transparent"
BorderThickness="0"
ItemsSource="{Binding PaymentsAndCollectionData.PaymentsToCreditors}"
SelectedItem="{Binding PaymentsAndCollectionData.SelectedPaymentToCreditor}">
<ListBox.ItemContainerStyle>
.......
</ListBox.ItemContainerStyle>
</ListBox
Now, I want to put a button in this style. So, I used a ControlTemplate like so (I know this looks weird, and I could propably have done this differently!):
<Style TargetType="ListBoxItem">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Button>
<Button.Style>
<Style TargetType="Button">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<Button Name="Button" HorizontalContentAlignment="Stretch" Background="Transparent" BorderThickness="0"
Command="{Binding RelativeSource={RelativeSource AncestorType=UserControl},
Path=DataContext.PaymentsAndCollectionData.SelectPaymentToCreditorCommand}"
CommandParameter="{Binding}">
<DockPanel Name="DP" LastChildFill="False" Background="{TemplateBinding Background}">
<TextBlock DockPanel.Dock="Left" Text="{Binding Name}" Margin="20,0,10,0" Padding="0,5,0,5" Foreground="{TemplateBinding Foreground}"/>
<StackPanel Orientation="Horizontal" DockPanel.Dock="Right">
<TextBlock Text="R" VerticalAlignment="Center" Foreground="{TemplateBinding Foreground}"/>
<TextBlock Text="{Binding Amount, StringFormat=N2}" VerticalAlignment="Center" Margin="0,0,10,0" Foreground="{TemplateBinding Foreground}"/>
</StackPanel>
</DockPanel>
</Button>
<ControlTemplate.Triggers>
<DataTrigger Binding="{Binding IsSelected}" Value="True">
<Setter TargetName="DP" Property="Background" Value="{StaticResource APPLICATION_GREEN_COLOR}" />
<Setter Property="Foreground" Value="White" />
</DataTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Button.Style>
</Button>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
So, the above works properly. The Name and Amount is set from the DataBinding. I am just failing to set the background, if IsSelected is true.
My binding object looks like this:
public class PaymentItem
{
public string Name { get; set; }
public decimal Amount { get; set; }
public bool IsSelected { get; set; }
}

Answer 1

If you change the IsSelected property after the object is created, you need to implement INotifyPropertyChanged interface in this object to make the Binding work.
public class PaymentItem : INotifyPropertyChanged
{
private bool _isSelected;
public string Name { get; set; }
public decimal Amount { get; set; }
public bool IsSelected
{
get
{
return _isSelected;
}
set
{
_isSelected = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}