>I am doing a little testing of calling an .APP program from .EXE (I am trying to break my application into several .APP programs so that the .EXE size would be reduced).
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>1. I create a small project that consisted of just one Form. Compiled it into test.app program. When I call this test.app from my "main" exe the form appears on the top of the existing application without affecting the existing application. When I close the form of test.app all goes back to normal, no changes to the main application. I like how it worked.
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>2. I created a small project that consisted of one .prg and one class library with a form class. The test.prg instantiates the form class and .shows() it. When I call this test.app program, it closes the form currently opened in the calling program (in .exe program). The form of test.app then appears. But I didn't like that the test.app closed the currently opened form.
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>My question is, what should I do in the main .prg program of the test.app to prevent it from closing forms of the calling program?

I would be surprised if it happens just because of calling test.app. Most likely some code in the test.app causes closing of the form in the main EXE.
Also keep in mind that while test.app runs in the context of the main EXE, it doesn't have access to any files built into EXE, like Forms, classes, reports, e.t.c.