[SOLVED] problem opening immediately to fullscreen

[pmh4514]

++ SOLVED++
The problem described below was because I had included CONFIG+=console in my PRO file
++++++++++

Hi, I'm using Qt 5.8, MSVC2015 64bit, Widgets application.

A very simple test app:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    MainWindow w;
    w.showMaximized();

    return a.exec();
}

MainWindow is just an empty widget with preferred horizontal and vertical size policies and no code within its constructor other than the call for ui->setupUi(this)

When I run the project from inside Qt Creator, I see what I expect to see - an empty full-screen window appears immediately.

However, when I run the compiled EXE by double-clicking it from Windows explorer, I first see a small black window (much like a command prompt but without the prompt) which lingers on screen for several seconds until finally the full-screen empty window appears. When I then close the full-screen MainWindow by clicking the X button in the top-right, that window closes, and I can see the original small black window left behind, and then that closes.

How can I eliminate this small black window that appears first?

Thanks!