more esoteric with the docs; center all by default; genericity without subject doesnt compile lol

layout/src/lib.rs

@@ -13,9 +13,11 @@ pub(crate) use ::tek_engine::*;
 pub(crate) use std::marker::PhantomData;
 
 #[cfg(test)] #[test] fn test_layout () -> Usually<()> {
+    let area: [u16;4] = [10, 10, 20, 20];
+    let unit = ();
+    //assert_eq!(().layout(area), [15, 15, 0, 0]); // should be independent over E, isn't
+    assert_eq!(Fill::x(()).layout(area), [10, 15, 20, 0]);
+    assert_eq!(Fill::y(()).layout(area), [15, 10, 0, 20]);
+    assert_eq!(Fill::xy(()).layout(area), area);
     Ok(())
 }
-
-#[cfg(test)] #[test] fn test_bsp () {
-    // TODO
-}