Add non-system-border option on Windows

Sine Striker

2023-12-22 c837319767bb609c6ec806336e49a347c77b11d3

 examples/mainwindow/mainwindow.qrc

@@ -1,5 +1,6 @@
<RCC>
    <qresource prefix="/">
        <file>dark-style.qss</file>
        <file>light-style.qss</file>
    </qresource>
</RCC>