Function render_composited 

pub fn render_composited(view: &ViewHandle, width: u32, height: u32) -> Rendered

Render view in a real window and capture it as the window server composited it, rather than as its own layers draw.

This is the only path that shows Liquid Glass. .glassEffect and .buttonStyle(.glass) are resolved by the compositor, not by the view’s layer tree, so cacheDisplayInRect renders them away and ImageRenderer drops the subtree — through either one a glass case passes without the glass ever existing.

Asks for nominal resolution so the result is in points and does not pick up the display’s backing scale.