Launch app and make top most window?

[softwareguy74]

I have a .NET WinForms application that has a single form that is set as TopMost so that it runs above all windows on the desktop.

This form has a single button on it to launch some other application, such as:

Dim app as Process
app = Process.Start("notepad")

How can I then make the app TopMost above my application which is already set to TopMost? In other words, notepad needs to be set as TopMost to bring it above my app. I assume this is a Win32 call of some sort. Thanks!

[chris128]

I'm sure the MSDN documentation for the TopMost property states that only other programs that are also marked as 'topmost' (like Task Manager for example) can appear on top of your form if you use the TopMost property. So you might find you have to make your other program TopMost as well (via Windows API) and then bring it to the front (again via Windows API).
For making a window TopMost you can use the SetWindowPos API http://msdn.microsoft.com/en-us/libr...45(VS.85).aspx
and I think that same API might also let you bring it to the front, but I've never tried using it for that.

[softwareguy74]

It is a third party app so I have no control over how that program is displayed. Hopefully I can figure out how to bring it to front, because so far setting the other program to top most with Win32 doesn't work. I probably have to do both somehow...

[chris128]

Post the code you are currently using

[softwareguy74]

Here is the calling code:

        Dim app As Process
        Try
            app = Process.Start("notepad")
            ptr = app.MainWindowHandle
            SetTopmostWindow(app.MainWindowHandle, True)
            SetForegroundWindow(app.MainWindowHandle)
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try

Here are the api declarations:

    Private Declare Function SetWindowPos Lib "user32" Alias "SetWindowPos" (ByVal _
        hwnd As Long, ByVal hWndInsertAfter As Long, ByVal x As Long, _
        ByVal y As Long, ByVal cx As Long, ByVal cy As Long, _
        ByVal wFlags As Long) As Long

    PublicDeclare Function SetForegroundWindow Lib "user32" (ByVal hwnd As IntPtr) As Long

    Public Sub SetTopmostWindow(ByVal hWnd As Long, Optional ByVal topmost As Boolean = True)
        Const HWND_NOTOPMOST = -2
        Const HWND_TOPMOST = -1
        Const SWP_NOMOVE = &H2
        Const SWP_NOSIZE = &H1
        SetWindowPos(hWnd, IIf(topmost, HWND_TOPMOST, HWND_NOTOPMOST), 0, 0, 0, 0, _
            SWP_NOMOVE + SWP_NOSIZE)
    End Sub

A key thing to remember is that the calling app window has been set as TopMost = True. I think that is the problem. It is conflicting with the ability to set Notepad on top of this window. But I need to do this because we are trying to lock the desktop until the user does something with the other app (notepad in this example), before closing our window.

[chris128]

Well you could test that theory by just setting the TopMost property for your app to False before you show Notepad couldnt you? Also, just making something TopMost will not stop the user from doing other things on the computer or 'lock' it.

[softwareguy74]

It seems that if my application form is set as TopMost, it is impossible to bring another window above it. If I turn off TopMost, it works. There should be a way to do this...

[Troy Lundin]

Here are the updated .Net declarations.

<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 UInt32) As Boolean
End Function

ReadOnly HWND_BOTTOM As New IntPtr(1)
ReadOnly HWND_NOTOPMOST As New IntPtr(-2)
ReadOnly HWND_TOP As New IntPtr(0)
ReadOnly HWND_TOPMOST As New IntPtr(-1)

<DllImport("user32.dll")> _
Private Shared Function SetForegroundWindow(ByVal hWnd As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean

[softwareguy74]

Sorry, that doesn't work either. No error, just doesn't bring Notepad on top of my window and doesn't make Notepad Topmost...

[Troy Lundin]

Take a look through here.