您好我已经在Wpf中创建了应用程序。我在这里面临的问题是，当我打开弹出窗口时，我已经放置了文件上载文件上传，当我点击上传文件的浏览按钮时，对话框在弹出窗口后面打开。但它应该在弹出窗口打开如果有人知道请帮助我。提前谢谢。
我的弹出窗口是这样的：
<Button Grid.Column="0" Grid.Row="0" x:Name="btnaddactivity" Width="140" Height="40" FontSize="12" Content="Save Project" Foreground="White" Background="#FFF3800C" Margin="631,425,99,-58" />
<Expander x:Name="expander" HorizontalAlignment="Right" FlowDirection="RightToLeft" Foreground="White" FontFamily="segoe_uilight" Height="200" Width="326" Canvas.Right="20" Canvas.Left="1000" BorderBrush="#FF0A0909" BorderThickness="1,1,1,2" Background="#FFF3800C" Margin="0,188,73,19" Loaded="expander_Loaded" >
<Expander.Header>
<StackPanel Orientation="Horizontal" Width="243">
<Canvas Height="22" Width="145" VerticalAlignment="Bottom">
<Image x:Name="imagebind1" Height="30" Width="45" RenderTransformOrigin="2.75,0.8" Canvas.Left="250" Canvas.Top="3" />
</Canvas>
</StackPanel>
</Expander.Header>
<Grid HorizontalAlignment="Left" Width="261" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="39*"/>
<ColumnDefinition Width="64*"/>
</Grid.ColumnDefinitions>
<ListBox ScrollViewer.HorizontalScrollBarVisibility="Disabled" BorderBrush="#FFF3800C" Name="icTodoList2" Background="#FFF3800C" Margin="23,10,-47,0" Grid.ColumnSpan="2" HorizontalAlignment="Left" Width="285" MouseUp="icTodoList2_MouseUp">
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/1.png" Height="30" Width="30" HorizontalAlignment="Center" />
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/2.png" Height="30" Width="30" HorizontalAlignment="Center" />
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/3.png" Height="30" Width="30" HorizontalAlignment="Center" Tag="-1"/>
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/4.png" Height="30" Width="30" HorizontalAlignment="Center" />
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/6.png" Height="30" Width="30" HorizontalAlignment="Center" />
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/7.png" Height="30" Width="30" HorizontalAlignment="Center" />
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/8.png" Height="30" Width="30" HorizontalAlignment="Center" />
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBoxItem>
<Canvas Margin="20,20,20,20" Height="30" Width="30" ClipToBounds="True" Background="#F39437" >
<StackPanel Orientation="Vertical">
<Image Source="img/icons/9.png" Height="30" Width="30" HorizontalAlignment="Center" />
</StackPanel>
</Canvas>
</ListBoxItem>
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel IsItemsHost="True" Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
</ListBox>
</Grid>
</Expander>
</Grid>
</Canvas>
</Border>
</Popup>