Make alignment a widget property

core/src/orientation/pos.rs

@@ -188,6 +188,15 @@ impl UiScalar {
         }
     }
 
+    /// Both channels by the same factor, which is what a fraction of a
+    /// length means when the length is part pixels and part a share.
+    pub const fn scale(&self, by: f32) -> Self {
+        Self {
+            rel: self.rel * by,
+            px: self.px * by,
+        }
+    }
+
     pub const fn offset(mut self, amt: f32) -> Self {
         self.px += amt;
         self