いまにゅーにお昼きかれたやつ、こうすればいいんじゃないん、って思ったやつ（その１）

MainPage.xaml

<StackPanel>
  <local:myControl MyButtonClick="MyButtonClick" />
  <Grid x:Name="HogeGrid" Visibility="Collapsed" />
</StackPanel>

MainPage.xaml.cs

public class MainPage : Page
{
  public MainPage()
  {
    InitializeComponents();
  }
  
  public void MyButtonClick(object sender)
  {
    HogeGrid.Visibility = Visibility.Visible;
  }
}

myControl.xaml

<Button Content="ぼたん" Click="ButtonClick" />

myControl.xaml.cs

public class myControl : UserControl
{
  public event EventHandler MyButtonClick;
  
  public myControl(){
    InitializeComponents();
  }
  
  public void ButtonClick(object sender, RoutedEventArgs args)
  {
    var h = MyButtonClick;
    if(h!=null) h(this);
  }
}