Issue with displaying a form with Show (not ShowModal)

[softtouch 9]

When I create a form which open another form and displays that with theform.show, so the code continue running (that form is some sort of "Please wait..." thing), the form will show up, but is somehow disabled and all controls on the main form are also not working anymore.

When I display the second form with theform.showmodal, all works and that second form is activated normal.

Is there any trick to display a form with show under macOS target?