diff --git a/src/layout/color.rs b/src/layout/color.rs
index 01f0457..c7d9ea6 100644
--- a/src/layout/color.rs
+++ b/src/layout/color.rs
@@ -44,8 +44,7 @@ impl<T: ColorNum> Color<T> {
     }
 }
 
-#[const_trait]
-pub trait F32Conversion {
+pub const trait F32Conversion {
     fn to(self) -> f32;
     fn from(x: f32) -> Self;
 }
diff --git a/src/layout/data.rs b/src/layout/data.rs
new file mode 100644
index 0000000..3c85abc
--- /dev/null
+++ b/src/layout/data.rs
@@ -0,0 +1,27 @@
+use std::any::{Any, TypeId};
+
+use crate::util::{HashMap, Id};
+
+#[derive(Default)]
+pub struct UiData {
+    map: HashMap<TypeId, Box<dyn Any>>,
+}
+
+impl UiData {
+    pub fn get<T: 'static>(&self) -> Option<&T> {
+        self.map
+            .get(&TypeId::of::<T>())
+            .map(|d| d.downcast_ref().unwrap())
+    }
+    pub fn get_mut<T: 'static>(&mut self) -> Option<&mut T> {
+        self.map
+            .get_mut(&TypeId::of::<T>())
+            .map(|d| d.downcast_mut().unwrap())
+    }
+
+    pub fn emit_remove(&mut self, id: &Id) {
+        for (tid, f) in &mut self.on_remove {
+            let data = self.map.get_mut(tid).unwrap().downcast_ref().unwrap();
+        }
+    }
+}
diff --git a/src/layout/num.rs b/src/layout/num.rs
index 571f728..c46b013 100644
--- a/src/layout/num.rs
+++ b/src/layout/num.rs
@@ -1,5 +1,4 @@
-#[const_trait]
-pub trait UiNum {
+pub const trait UiNum {
     fn to_f32(self) -> f32;
 }
 
diff --git a/src/util/math.rs b/src/util/math.rs
index 744889b..e4e6600 100644
--- a/src/util/math.rs
+++ b/src/util/math.rs
@@ -1,13 +1,11 @@
 use std::ops::*;
 
-#[const_trait]
-pub trait LerpUtil {
+pub const trait LerpUtil {
     fn lerp(self, from: Self, to: Self) -> Self;
     fn lerp_inv(self, from: Self, to: Self) -> Self;
 }
 
-#[const_trait]
-pub trait DivOr {
+pub const trait DivOr {
     fn div_or(self, rhs: Self, other: Self) -> Self;
 }