Add non-system-border option on Windows

Sine Striker

2023-12-22 c837319767bb609c6ec806336e49a347c77b11d3

 src/core/contexts/cocoawindowcontext.mm

@@ -400,4 +400,17 @@
        cocoaWindowEventFilter = std::make_unique<CocoaWindowEventFilter>(this, this);
    }

    bool CocoaWindowContext::windowAttributeChanged(const QString &key, const QVariant &attribute,
                                                    const QVariant &oldAttribute) {
        if (key == QStringLiteral("no-system-buttons")) {
            if (attribute.toBool()) {
                // TODO: set off
            } else {
                // TODO: set on
            }
            return true;
        }
        return false;
    }

}