VB.NET Send Tab key to another application window - vb.net

Question

I want to send "{TAB}" Key to another application window(send the key to the window not to textbox).
I tried:
SendMessage(hWnd, WM_SETHOTKEY, VK_TAB, 0)
Nothing happened.
my goal is:
send tab key to my application Or other application when the application window is not in focus.
(i know that sendkey is not professional in this case there is no choice(This is the first time that I'm using it).)
I made many attempts and I always returned to the same result:
Nothing happened.
Does anyone know the answer?

Answer 1

SendKeys requires the application that you are sending the Keys to, to be active.
From above Link:
Use SendKeys to send keystrokes and keystroke combinations to the active application.
I order to get around this limitation you will have to resort to using the WinApi Functions.
FindWindow pInvoke.net
FindWindowEx pInvoke.net
sendMessage pInvoke.net
See this MSDN Forum Post for an example
Here is a modified example from that Posting:
Public Class Form1
Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
(ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr
Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
(ByVal hWnd As IntPtr, ByVal hWndChildAfterA As IntPtr, ByVal lpszClass As String, ByVal lpszWindow As String) As IntPtr
Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hWnd As IntPtr, ByVal wMsg As Integer, ByVal wParam As IntPtr, ByVal lParam As String) As IntPtr
Const WM_SETTEXT As Integer = &HC
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim destination As IntPtr = FindWindow(Nothing, "Untitled - Notepad")
Dim destControl As IntPtr = FindWindowEx(destination, IntPtr.Zero, "Edit", Nothing)
SendMessage(destControl, WM_SETTEXT, IntPtr.Zero, "Hello" & vbTab & "GoodBye" & vbCrLf)
End Sub
End Class
Added an Additional Example using WM_KEYDOWN I created another small application with the Window Title set to TestForm and overrode the WndProc Method to determine if the application got the TabKey.
Sending Form
Public Class Form1
Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
(ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr
Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hWnd As IntPtr, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As IntPtr
Const WM_KEYDOWN As Integer = &H100
Const VK_TAB As Integer = &H9
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim destination As IntPtr = FindWindow(Nothing, "TestForm")
SendMessage(destination, WM_KEYDOWN, VK_TAB, 0)
End Sub
End Class
Test Form
Put a breakpoint on MyBase.WndProc(m) and look at m to see what has been sent.
Public Class Form1
Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
MyBase.WndProc(m)
End Sub
End Class

Answer 2

Having struggled with this type of this a few times before, i would suggest a couple of things to look at.
The 1st is autoit which includes a dll you can reference from vb.net, and is very simple you use, and well documented. I tend to use that whenever i need to control a 3rd party program.
The other is the ui automation classes
See this for an example:
http://blog.functionalfun.net/2009/06/introduction-to-ui-automation-with.html

Answer 3

you need make the other window active first. check Change focus to another window in VB.NET . then use send key.