PopUp Dialog Behaviour

Based on the StaffLynx application’s modal control-based popups and inspired by this post by Brad, I set about creating a PopUp Dialog Blend Behaviour and sample which I have put into the Expression Gallery.


The behaviour allows for Dialogs to be easily added to a WPF application. If the dialog is Modal, it is modal to any part of the window (not just the whole window) i.e. a Tab. This allows for non-linear application navigation as the entire window is not locked down.

The behaviour is applied to any grid (other panels aren’t supported at the moment), if it is modal this will be the area that is disabled when the dialog appears. The showing and hiding of the dialog is controlled by the Visible dependency property on the behaviour, and the modal drum skins color and opacity can be set. There is currently no support for animation, but could easily be added (please send in the changes if you do 🙂 )

The dialog is any UiElement as in this sample is a usercontrol (line 5).

Behavior XAML from the Sample

<Grid Grid.Row="1">
        <ch:PopUpBehaviour x:Name="SampleDialog" Modal="true" Visible="{Binding ElementName=Go, Path=IsChecked, Mode=TwoWay}">
            <Sample:Dialog />
            <ch:DisableBackGroundBehaviour Background="Pink" />

The main reason I started looking into alternatives to Brad’s solution was a better separation of visuals and behaviour, primarily ease of styling of the actual dialog.  It also puts any behaviour requirements in the hands of the dialog designer. If you want dragability or resiziability you have to implement it, thankfully it’s as easy as adding other blend behaviours. The below code snippet is the contents of a sample dialog, it can be any UiElement .

Dialog XAML from the Sample

 <Border BorderThickness="1" Background="BlanchedAlmond"  Width="150" Height="150">
      <il:MouseDragElementBehavior ConstrainToParentBounds="True"/>
      <DockPanel Background="White" Opacity="1" Margin="1">
        <UniformGrid DockPanel.Dock="Bottom">
          <Button Command="ApplicationCommands.Close" Width="50">Close</Button>
        <TextBlock DockPanel.Dock="Top" Text="Dialog" />

To Close the dialog you can either set the behaviour Visible property to false or execute the ApplicationCommands.Close command as per the sample. (Line 8 in the dialog)

A more MVVM oriented Dialog Service based on this behaviour will soon be released in Present.