How to make a borderless window staying on the top of the system?

[moiit]

setWindowFlags(Qt::WindowStaysOnTopHint);
setWindowFlags(Qt::FramelessWindowHint);

setWindowFlags(Qt::WindowStaysOnTopHint);
setWindowFlags(Qt::FramelessWindowHint);

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Use this, the window is borderless, but it does not stay on top.

setWindowFlags(Qt::FramelessWindowHint);
setWindowFlags(Qt::WindowStaysOnTopHint);

setWindowFlags(Qt::FramelessWindowHint);
setWindowFlags(Qt::WindowStaysOnTopHint);

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The window stays on top, but it has a border.

Please help, thanks!