listview不会仅在第二次更新

Question

我在WPF中有一个listview，它不会添加第二行，直到添加第三行然后全部三个渲染。每个下一行正确且立即呈现。 我真的不知道为什么只在第二次发生这种情况。

wpf代码：

          <ListView Name="DownloadList" Background="WhiteSmoke" PreviewMouseRightButtonUp="DownloadList_PreviewMouseRightButtonUp" >
                <ListView.View>
                    <GridView>
                        <GridViewColumn Width="140" Header="Name" DisplayMemberBinding="{Binding Name}"/>
                        <GridViewColumn Width="80" Header="Status" DisplayMemberBinding="{Binding Status}"/>
                        <GridViewColumn Width="60" Header="Size" DisplayMemberBinding="{Binding FormattedSize}"/>
                        <GridViewColumn Width="70" Header="Speed" DisplayMemberBinding="{Binding FormattedSpeed}"/>
                        <GridViewColumn Width="170" Header="Progress">
                            <GridViewColumn.CellTemplate>
                                <DataTemplate>
                                    <ProgressBar Height="20" Width="150" Maximum="{Binding Size}" Value="{Binding Progress}"/>
                                </DataTemplate>
                            </GridViewColumn.CellTemplate>
                        </GridViewColumn>
                        <GridViewColumn Width="65" Header="Time Left" DisplayMemberBinding="{Binding FormattedTime}"/>
                        <GridViewColumn Width="60" Header="Peers" DisplayMemberBinding="{Binding Peers}"/>          
                    </GridView>
                </ListView.View>
            </ListView>

代码背后的

：

        FileDownload download = new FileDownload(fileToDownload.id, fileToDownload.DownloadName,(int)fileToDownload.Length, partsData.Length);
        wpfDownloads.Add(download);