One instance of app

[chongo 2002]

How do i keep a user from opening more than one of the same vb application? I want only one to be able to be run at a time, unlike msword that can run multiple times.

[PITBULLCJR]

If App.PrevInstance = True Then
Unload Me
End If

[beachbum]

Hi
I got this code on this forum somewhere. It is better than using the App.Previnstance / unload method because it actually jumps to the currently running instance of ur project.
Regards
Stuart

Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
(ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Declare Function GetWindow Lib "user32" (ByVal hwnd As Long, _
ByVal wCmd As Long) As Long
Declare Function OpenIcon Lib "user32" (ByVal hwnd As Long) As Long
Declare Function SetForegroundWindow Lib "user32" (ByVal _
hwnd As Long) As Long
         
Public Const GW_HWNDPREV = 3
 
Public Sub ShowPrevInstance()
    On Error Resume Next
    Dim OldTitle As String
    Dim ll_WindowHandle As Long
    'saving the current title in OldTitle variable and changing the application title
    OldTitle = App.Title
    App.Title = "New App - This App Will Be Closed"
    'finding the previous instance. if you are using VB 5.0 change "ThunderRT6Main" to "ThunderRT5Main"
    ll_WindowHandle = FindWindow("ThunderRT6Main", OldTitle)
    'if there is no old instances of your application - exit.
    If ll_WindowHandle = 0 Then Exit Sub
    'Find the window we need to restore
    ll_WindowHandle = GetWindow(ll_WindowHandle, GW_HWNDPREV)
    'Now restore it
    Call OpenIcon(ll_WindowHandle)
    'And Bring it to the foreground
    Call SetForegroundWindow(ll_WindowHandle)
    Unload Me
    Set [Your Form Name Here] = Nothing
End Sub

[chongo 2002]

thanks

[chongo 2002]

On the last line does the title go inside [] or did you just put those there as markers? show me an example just to make sure i understand.

[beachbum]

Hi
Just insert the name of the form that loads at start up in ur app
So, if it is form1 do...

Set Form1 = Nothing

You dont even need this line in all cases but does no harm
Regards
Stuart

[chongo 2002]

got ya

[chongo 2002]

Ok the code works in the case that it willnot allow another application to open but it does not popup the running application do you know why?

[beachbum]

Hi again
It works but i hope that you actually called the routine...
In ur Sub Main or Form Load or wherever your project starts u need to call the routine

If App.PrevInstance Then ShowPrevInstance

Regards
Stuart

[chongo 2002]

Thanks that code works great

[Sibby]

I don't know about VB6, but VB5's class window name is "ThunderRT5Form", NOT "ThunderRT5Main".

NOTE: You can find the classname of any window using "Find window" option in SPY++ (bundled with VC++). It's very easy and it's helped me out alot recently.

::Sibby::