The direct equivalent of "e is MyType" would be "TypeOf e Is MyType":
If TypeOf e Is RenderEventBubbleEventArgs Then
Dim re As RenderEventBubbleEventArgs = TryCast(e, RenderEventBubbleEventArgs)
...
However, the original code is inefficient, as it attempts to cast the value twice for each type. It would be better to use:
var reb = e as RenderBubbleEventArgs;
if (reb != null)
{
...
return;
}
which would translate as:
Dim reb As RenderEventBubbleEventArgs = TryCast(e, RenderEventBubbleEventArgs)
If reb IsNot Nothing Then
...
Return
End If
http://www.developerfusion.com/tools/convert/csharp-to-vb/