Function render_window_decoration 

pub fn render_window_decoration(
    buffer: &mut [u32],
    buf_w: u32,
    config: &DecorationConfig,
    title: &str,
    focused: bool,
    width: u32,
    height: u32,
)

Render a complete window decoration frame into a pixel buffer.

Draws the title bar (with title text), border outline, and close/maximize/ minimize buttons. The buffer is expected to include space for decorations: total width = width, total height = height (title bar at top, border around all edges).

Pixels are written as 0xAARRGGBB (ARGB8888).