elementhost里面的表单是透明的

Question

我创建了一个带有elementhost的表单来保存我的usercontrol（xaml）。单击一个按钮时，一切都正常工作，除了我的usercontrol（xaml）也是透明的，我不希望它。任何人都可以对这个问题有所了解吗？

frmShow.Designer.cs

private void InitializeComponent()
{
    this.elementHost1 = new System.Windows.Forms.Integration.ElementHost();
    this.loadingImage1 = new LoadingImage.WPF.Views.LoadingImage();
    this.SuspendLayout();
    // 
    // elementHost1
    // 
    this.elementHost1.Dock = System.Windows.Forms.DockStyle.Fill;
    this.elementHost1.Location = new System.Drawing.Point(0, 0);
    this.elementHost1.Name = "elementHost1";
    this.elementHost1.Size = new System.Drawing.Size(284, 262);
    this.elementHost1.TabIndex = 0;
    this.elementHost1.Text = "elementHost1";
    this.elementHost1.Child = this.loadingImage1;
    // 
    // frmShow
    // 
    this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
    this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
    this.BackColor = System.Drawing.Color.Black;
    this.ClientSize = new System.Drawing.Size(284, 262);
    this.Controls.Add(this.elementHost1);
    this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
    this.Name = "frmShow";
    this.Opacity = 0.5D;
    this.Text = "frmShow";
    this.WindowState = System.Windows.Forms.FormWindowState.Maximized;
    this.ResumeLayout(false);

} 

LoadingImage.xaml

<UserControl
    x:Class="Test.WPF.Views.LoadingImage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    Height="100"
    Width="100">
    <Grid>
        <Rectangle
            HorizontalAlignment="Stretch"
            VerticalAlignment="Stretch"
            Opacity="0.6"
            Fill="Gray" />
        <Border
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            BorderBrush="Red"
            BorderThickness="3"
            Background="Green"
            CornerRadius="8">
            <TextBlock
                HorizontalAlignment="Center"
                Margin="20,10"
                VerticalAlignment="Center"
                FontFamily="Arial"
                FontSize="18.667"
                Foreground="White"
                TextWrapping="Wrap"
                Text="Tesing" />
        </Border>
    </Grid>
</UserControl>