refactor project structure (start of redoing atomic branch without atomics)

src/widget/ptr.rs

@@ -0,0 +1,30 @@
+use crate::prelude::*;
+
+#[derive(Default)]
+pub struct WidgetPtr {
+    pub inner: Option<WidgetId>,
+}
+
+impl Widget for WidgetPtr {
+    fn draw(&mut self, painter: &mut Painter) {
+        if let Some(id) = &self.inner {
+            painter.widget(id);
+        }
+    }
+
+    fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len {
+        if let Some(id) = &self.inner {
+            ctx.width(id)
+        } else {
+            Len::ZERO
+        }
+    }
+
+    fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len {
+        if let Some(id) = &self.inner {
+            ctx.height(id)
+        } else {
+            Len::ZERO
+        }
+    }
+}