I used LogonUser and CreateProcessAsUser API functions to start an executable with user credentials different from the current ones.

Very simple executable programmed to display MessageBox with SYS(0) information -- to confirm that the user really changed.

Only window titles of the main FoxPro window and that MessageBox partially appeared. Visibly there was a drawing conflict, if I may say so. Though I was able to close the MessageBox pressing Enter.

May be I missed some flags while running CreateProcessAsUser. Certainly I will return to that code to get more from this functionality.

Another executable sending email messages did Ok, though WAIT WINDOW was drawn partially, only the border of it.