public Style PopupStyle { get; set; }

Public Property PopupStyle As Style

<Style TargetType="local:SchedulePopupContent">
  <Setter Property="BorderBrush" Value="{StaticResource PopupContentBorderBrush}" />
  <Setter Property="BorderThickness" Value="1" />
  <Setter Property="Background" Value="{StaticResource PopupContentBackgroundBrush}" />
  <Setter Property="Padding" Value="2" />
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="local:SchedulePopupContent">
        <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}">
          <StackPanel Orientation="Vertical">
            <StackPanel Name="NameContainer" Orientation="Horizontal">
              <TextBlock Text="{Binding DataContext.ActivityName}" FontWeight="Bold" />
              <TextBlock Text=" (" />
              <TextBlock Text="{Binding DataContext.ScheduleMode}" />
              <TextBlock Text=")" />
            </StackPanel>
            <StackPanel Name="StartTimeContainer" Orientation="Horizontal">
              <TextBlock Text="Start time: " />
              <TextBlock Text="{Binding ExpectedStartTime}" />
            </StackPanel>
            <StackPanel Name="EndTimeContainer" Orientation="Horizontal">
              <TextBlock Text="End time: " />
              <TextBlock Text="{Binding ExpectedEndTime}" />
            </StackPanel>
            <StackPanel Name="DurationContainer" Orientation="Horizontal">
              <TextBlock Text="Duration: " />
              <TextBlock Text="{Binding ExpectedDuration}" />
            </StackPanel>
            <StackPanel Name="ProgressContainer" Orientation="Horizontal" >
              <TextBlock Text="Progress: " />
              <TextBlock Text="{Binding ExpectedProgress}" />
            </StackPanel>
          </StackPanel>
        </Border>
        <ControlTemplate.Triggers>
          <Trigger Property="Action" Value="ResizeStart">
            <Setter TargetName="StartTimeContainer" Property="Visibility" Value="Visible" />
            <Setter TargetName="EndTimeContainer" Property="Visibility" Value="Collapsed" />
            <Setter TargetName="ProgressContainer" Property="Visibility" Value="Collapsed" />
          </Trigger>
          <Trigger Property="Action" Value="ResizeEnd">
            <Setter TargetName="StartTimeContainer" Property="Visibility" Value="Collapsed" />
            <Setter TargetName="EndTimeContainer" Property="Visibility" Value="Visible" />
            <Setter TargetName="ProgressContainer" Property="Visibility" Value="Collapsed" />
          </Trigger>
          <Trigger Property="Action" Value="Move">
            <Setter TargetName="StartTimeContainer" Property="Visibility" Value="Visible" />
            <Setter TargetName="EndTimeContainer" Property="Visibility" Value="Visible" />
            <Setter TargetName="ProgressContainer" Property="Visibility" Value="Collapsed" />
          </Trigger>
          <Trigger Property="Action" Value="ResizeProgress">
            <Setter TargetName="StartTimeContainer" Property="Visibility" Value="Collapsed" />
            <Setter TargetName="EndTimeContainer" Property="Visibility" Value="Collapsed" />
            <Setter TargetName="ProgressContainer" Property="Visibility" Value="Visible" />
          </Trigger>
        </ControlTemplate.Triggers>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>