Andi,

I found the answers for the server side click event of WebFishEyeStackButton & WebFishEyeButton.

for WebFishEyeButton:
in WebFishEye property set ButtonClick event to the name of the event in code behind.
give every button unique ItemName in its property.
and then in the code behind event, with the parameter WebFishEyeButtonEventArgs e, use e.button to get the itemName. so it knows which button is clicked.
by select case/if else, implemet the expected functions.

for WebFishEyeStackButton:
in WebFishEye property set StackButtonClick event to the name of the event in code behind.
give every button unique ItemName in its property.
and then in the code behind event, with the parameter WebFishEyeButtonEventArgs e, use e.button to get the itemName. so it knows which button is clicked.
by select case/if else, implemet the expected functions.

in XAML:

<ISNet_Silverlight_WebAqua:WebFishEye Height="128" HorizontalAlignment="Left"  ..............
StackButtonClick="WebFishEye_StackButtonClick" ButtonClick="WebFishEye_ButtonClick">

in Code Behind:

private void WebFishEye_StackButtonClick(object sender,WebFishEyeButtonEventArgs e)

{ 
 WebFishEyeStackButton btn = (WebFishEyeStackButton)e.Button;
 if (btn.ItemName == "gtafCalendar")
 {
   forumCalendar.Visibility = Visibility.Visible;
  }
}

private void WebFishEye_ButtonClick(object sender, WebFishEyeButtonEventArgs e)

{
   WebFishEyeButton btn = (WebFishEyeButton)e.Button;
   if (btn.ItemName == "News")
   { 
     penalNews.Visibility = Visibility.Visible;
   }
}