This quick test VI, when run in the dev env, immediately hides its front panel and the taskbar item for it disappears too, then two seconds later it sounds the PC beep, then closes itself an additional second later. The beep is purely there so that I know the VI is still running and not quit out.
This hidden front panel is the behaviour I want for my VI. But when I build an executable from it and run it, the item in the Windows Task Bar remains. It's there for the duration (three seconds), then vanishes when the VI closes.
So, why does the built executable cause a visible taskbar ite