shell command

Hello
I have problems with the "shell" command.
With this command, I launch another program which last between 1 and 3 seconds.
First of all, I would like this program to be launched in background instead of masking my B4PPC window.
Then, I would like that my B4PPC program could wait for the program launched by the shell command to be finished. For example, a first image (it is an animated gif) would appear before the shell, and another one just after.

Here is my actual code :

Sub dire
Image1.Image=AppPath & "\image1.gif"
Shell(AppPath & "\ptts.exe" , "-u " & AppPath & "\alice.txt")
Sleep(3000)
Image1.Image=AppPath & "\image2.png"
End Sub

Thank you for your help.

Use the Process object from my http://www.b4x.com/forum/additional-libraries/4805-threading-library-version-2-a.html#post27720 to launch your app. It will give you an event for when the application finishes, or you could use its WaitForExit method in a loop.

I don't think there is a way to start it without it coming to the front.

Thank you, it works well.
But if someone else could have an idea to run an app in minimized window.... it would be fine.