there is a very useful function "IsAppRunning()" in hmg. It prevents me to launch an app, that's already running. But, it won't work on a netfolder, at least that is what I have experienced. If I am wrong, tell me and do not continue reading.
The reason why I came to hmg (thank you Roberto Lopez), was, I had some small apps with UI like "from date"-"to date" (mostly reports). I did them all with xbase++ in text mode and excel made them "good-looking". xbase++ is powerful, but I did never try to go GUI. Too difficult for a non professional like me.
In the meantime almost all my apps were rewritten to hmg (professional look and feel, people saying: "hey, he's gone windows"). But then I created an app, that really needs GUI. With the help from this forum it is done to 99%. For me 2 weeks are left to go up to 100%. I will.

This app is on a netfolder to which 3-4 users have access. To prevent, that more than 1 user can start the program I came to the following solution:
Any time the program is launched, the field "username" in a table is replaced by "GetComputerName()" and the program can not be started. When the program is finished, "username" is replaced with spaces.
Before I realize that, has anyone a better suggestion?
I'm looking forward to your suggestions.
Robert