Sergey,

Thank you for your answer.

The solution suggested résoud unfortunately not the problem.
I will try to explain the problem again.
I open the tasklist Manager by the order DO (_ TASKLIST) which is in the start program (Startcb.prg)
(the result is identical with KEYBOARD "DO (_ TASKLIST) {ENTER}{CTRL+F2}" CLEAR PLAIN"

The window 'command' is active
I launch the application by " DO main.prg."
The first the program launches out normally.

When I finish the application, I give the taslist Manager on the desk by DO (_ TASKLIST) or
KEYBOARD " DO (_ TASKLIST) {ENTER}{CTRL+F2}" CLEAR PLAIN" in the code.

The window 'command' is active.
If I try to again launch the application by "DO main.prg." the program does not start any more.
The taskmanager List becomes active!

Bernhart