Qt + DirectFB not working window drag

[Sung Sean]

Hello.

I using Qt embedded 4.8.6 with DirectFB 1.2.8.

I write simple code like below.

#include <QApplication>
#include <QMainWindow>

int main(int argc, char** argv)
{
    QApplication app(argc, argv);

    QMainWindow win;
    win.show();

    return app.exec();
}

When I grab window's title bar and drag using my mouse device(for windows move),
my display showing below linked image.

https://drive.google.com/file/d/0B8Wbvmr8DTE2MmdiZlVGU3k1eWdEZWNEOVhmbmhZTjBjWUtN/view?usp=sharing

What is wrong?

Thank you.

[Sung Sean]

I found solution and comment for other person.

When I set 'bg-color' to 'transparent(0x00000000)' in .directfbrc,
DFB don't update framebuffer.

So, I set bg-color to 'magenta color(0x00FF00FFFF)' in .directfbrc,
and I set colorkey to my framebuffer, it works fine.