How Can I Open a WPF Popup with a Delay?

You can create a style to be applied to the Popup in the following way:

<Style x:Key="TooltipPopupStyle" TargetType="Popup">    <Style.Triggers>        <DataTrigger Binding="{Binding PlacementTarget.IsMouseOver, RelativeSource={RelativeSource Self}}" Value="True">            <DataTrigger.EnterActions>                <BeginStoryboard x:Name="OpenPopupStoryBoard" >                    <Storyboard>                        <BooleanAnimationUsingKeyFrames Storyboard.TargetProperty="IsOpen" FillBehavior="HoldEnd">                            <DiscreteBooleanKeyFrame KeyTime="0:0:0.25" Value="True"/>                        </BooleanAnimationUsingKeyFrames>                    </Storyboard>                </BeginStoryboard>            </DataTrigger.EnterActions>            <DataTrigger.ExitActions>                <PauseStoryboard BeginStoryboardName="OpenPopupStoryBoard"/>                <BeginStoryboard x:Name="ClosePopupStoryBoard">                    <Storyboard>                        <BooleanAnimationUsingKeyFrames Storyboard.TargetProperty="IsOpen" FillBehavior="HoldEnd">                            <DiscreteBooleanKeyFrame KeyTime="0:0:1" Value="False"/>                        </BooleanAnimationUsingKeyFrames>                    </Storyboard>                </BeginStoryboard>            </DataTrigger.ExitActions>        </DataTrigger>        <Trigger Property="IsMouseOver" Value="True">            <Trigger.EnterActions>                <PauseStoryboard BeginStoryboardName="ClosePopupStoryBoard" />            </Trigger.EnterActions>            <Trigger.ExitActions>                <PauseStoryboard BeginStoryboardName="OpenPopupStoryBoard"/>                <ResumeStoryboard BeginStoryboardName="ClosePopupStoryBoard" />            </Trigger.ExitActions>        </Trigger>    </Style.Triggers></Style>

Then, whenever you want to use it, you would write markup similar to this (notice the binding for the PlacementTarget):

<TextBlock x:Name="TargetControl" Text="Hover over me!" /><Popup PlacementTarget="{Binding ElementName=TargetControl}" Style="{StaticResource TooltipPopupStyle}">    <Border BorderBrush="Red" BorderThickness="1" Background="White">        <TextBlock Text="This is a Popup behaving somewhat like the tooltip!" Margin="10" />    </Border></Popup>

The answer cplotts pasted is good but may not apply in your case because it leaves the animation attached to the IsOpen property, effectively locking it in place and preventing it from being changed via direct property setting, binding, and other ways. This may make it difficult to use with your code, depending on how you are using it.

If that is the case, I would switch to starting a DispatcherTimer when you want to open a popup after some delay, like this:

_popupTimer = new DispatcherTimer(DispatcherPriority.Normal);_popupTimer.Interval = TimeSpan.FromMilliseconds(100);_popupTimer.Tick += (obj, e) =>{  _popup.IsOpen = true;};_popupTimer.Start();

For a ToolTip-like behavior this could be done on MouseEnter. If you want to cancel the popup opening for some reason (such as if the mouse leaves the control before the popup appears), just:

_popupTimer.Stop();

Update

As cplotts obseved in the comment, you will also want to set _popup.IsOpen = false in some situations in the MouseLeave event, depending on your logic for handling the mouse enter / exit events between your control and the popup. Be aware that you usually don't want to blindly set IsOpen=false on every MouseLeave event, because it may do so when the popup appears over it. This would in some situations lead to a flickering popup. So you'll need some logic there.

First off ... the credit for this answer goes to Eric Burke. He answered this very question posted in the WPF Disciples group. I thought it would be useful to put this answer out on StackOverflow too.

Basically, you need to animate the IsOpen property of the Popup with with a DiscreteBooleanKeyFrame.

Check out the following xaml (which can easily be pasted into Kaxaml or another loose xaml editing utility):

<Page    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">    <ContentPresenter>        <ContentPresenter.ContentTemplate>            <DataTemplate>                <Grid>                    <CheckBox                        x:Name="cb"                        Width="100"                        Height="40"                        Content="Hover Over Me"                    />                    <Popup                        x:Name="popup"                        Placement="Bottom"                        PlacementTarget="{Binding ElementName=cb}"                    >                        <Border Width="400" Height="400" Background="Red"/>                    </Popup>                </Grid>                <DataTemplate.Triggers>                    <Trigger SourceName="cb" Property="IsMouseOver" Value="True">                        <Trigger.EnterActions>                            <BeginStoryboard x:Name="bsb">                                <Storyboard>                                    <BooleanAnimationUsingKeyFrames                                        Storyboard.TargetName="popup"                                        Storyboard.TargetProperty="IsOpen"                                        FillBehavior="HoldEnd"                                    >                                        <DiscreteBooleanKeyFrame KeyTime="0:0:0.5" Value="True"/>                                     </BooleanAnimationUsingKeyFrames>                                </Storyboard>                            </BeginStoryboard>                        </Trigger.EnterActions>                        <Trigger.ExitActions>                            <StopStoryboard BeginStoryboardName="bsb"/>                        </Trigger.ExitActions>                    </Trigger>                </DataTemplate.Triggers>            </DataTemplate>        </ContentPresenter.ContentTemplate>    </ContentPresenter></Page>

Please note that I modified his original solution slightly ... to trigger the IsOpen on mouse over versus checking the CheckBox as he had it. All in the attempt to make Popup behave a little like ToolTip.