Launch an application and "force" focus if an error occurs? - vb.net

Question

I have a scaling program used in our shipping department. The user scans a carton, it handles some database processing, and inserts a record identifying that carton into a "queue" table. The scale program also starts up a separate .exe which handles label processing (making calls to FedEx or UPS, or building custom ZPLs depending on what is needed, then sends to the printers attached to the machine). These PCs are Windows 7, if that makes a difference.
Occasionally a bad piece of data will cause an error in the label program. We recently discovered that one of our customers do not require a valid phone number when one of their customers place an order, and if the carton ends up shipping FedEx Home Delivery or SmartPost where a phone number is required, the API returns an error.
The print label program's error messages are popping up behind the scale program. Is there a way to force the error messages from the print label program to the top of any other open windows?
EDIT: I am calling the label program by first checking to see if there is a process running with the .exe's name. If not, it calls a launcher utility which looks on our app server to see if an updated exe is available, and copies to the c:\tmp directory if it is. Then runs the local c:\tmp copy of the program for that machine.

Answer 1

One way to accomplish this is to set your error form as a TopMost window. If you would always like the form to be above all other windows (including windows from other processes), add this to your form:
Private Const WS_EX_TOPMOST As Integer = &H00000008
Protected Overrides ReadOnly Property CreateParams() As CreateParams
Get
Dim cp As CreateParams = MyBase.CreateParams
cp.ExStyle = cp.ExStyle Or WS_EX_TOPMOST
Return cp
End Get
End Property
This code overrides CreateParams for the window, adding in the TOPMOST flag. You don't have to do anything after this - the window will always be topmost.
You can also use the p/Invoke SetWindowPos to make the window topmost on-demand:
<DllImport("user32.dll", SetLastError:=True)>
Private Shared Function SetWindowPos(ByVal hWnd As IntPtr, ByVal hWndInsertAfter As IntPtr, ByVal X As Integer, ByVal Y As Integer, ByVal cx As Integer, ByVal cy As Integer, ByVal uFlags As Integer) As Boolean
End Function
Private Shared ReadOnly HWND_TOPMOST As New IntPtr(-1)
Private Shared ReadOnly HWND_NOTOPMOST As New IntPtr(-2)
Private Const SWP_NOSIZE As Integer = &H1
Private Const SWP_NOMOVE As Integer = &H2
Public Sub SetWindowAsTopMost()
SetWindowPos(Handle, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE Or SWP_NOSIZE)
End Sub