Hi

In .NET 2.0, the MessageBox has four options as below.
MessageBoxOptions Enumeration
DefaultDesktopOnly The message box is displayed on the active desktop.
This constant is the same as ServiceNotification except that the system
displays the message box only on the default desktop of the interactive
window station.

RightAlign The message box text is right-aligned.  
RtlReading Specifies that the message box text is displayed with right to
left reading order.  
ServiceNotification The message box is displayed on the active desktop.
The caller is a service notifying the user of an event. The function
displays a message box on the current active desktop, even if there is no
user logged on to the computer.

So if you want to get the MB_TOPMOST style, you need to MessageBox API.

From the 2.0 MSDN, we have no such methods, we have the parent property but
it is readonly.
Parent   Gets a reference to the server control's parent control in the
page control hierarchy. (Inherited from Control.)  

Also there are methods AddOwnedForm and RemoveOwnedForm , you may take a
look to see if that helps you.

We have some functions may help to do search windows in 2.0 you have a look.
FindForm  
FromHandle  
FromChildHandle  

Best regards,

Peter Huang
Microsoft Online Partner Support