Function floating_drag_grip 

pub fn floating_drag_grip(
    scene: &mut Scene,
    transform: Affine,
    rect: Rect,
    color: AlphaColor<Srgb>,
)

Shared quiet drag affordance for a detachable soft surface.

Call, navigation and generic floating windows use the same 36×3 logical pixel pill. Keeping this out of app renderers makes the cross-boundary gesture recognizable without imposing one shared title/control layout on workflow-specific surfaces.