switch to element defined span lens + better size fn

src/core/position/align.rs

@@ -7,11 +7,12 @@ pub struct Aligned {
 
 impl Widget for Aligned {
     fn draw(&mut self, painter: &mut Painter) {
-        let region = UiRegion::from_ui_size_align(painter.size(&self.inner), self.align);
+        let region =
+            UiRegion::from_ui_size_align(painter.size(&self.inner).to_uivec2(), self.align);
         painter.widget_within(&self.inner, region);
     }
 
-    fn desired_size(&mut self, ctx: &mut SizeCtx) -> UiVec2 {
+    fn desired_size(&mut self, ctx: &mut SizeCtx) -> Size {
         ctx.size(&self.inner)
     }
 }