diff --git a/src/core/sense.rs b/src/core/sense.rs
index 455b42f..7a7ed95 100644
--- a/src/core/sense.rs
+++ b/src/core/sense.rs
@@ -264,13 +264,9 @@ impl<E: Event<Ctx, Data = <Senses as Event<Ctx>>::Data> + Into<Senses>, Ctx: 'st
         });
     }
 
-    fn run<'a>(
-        &mut self,
-        id: &Id,
-        event: E,
-    ) -> Option<impl Fn(&mut Ctx, E::Data) + use<'a, E, Ctx>> {
+    fn run<'a>(&self, id: &Id, event: E) -> Option<impl Fn(&mut Ctx, E::Data) + use<'a, E, Ctx>> {
         let senses = event.into();
-        if let Some(group) = self.map.get_mut(id) {
+        if let Some(group) = self.map.get(id) {
             let fs: Vec<_> = group
                 .sensors
                 .iter()
diff --git a/src/layout/event.rs b/src/layout/event.rs
index ad043f7..64a88af 100644
--- a/src/layout/event.rs
+++ b/src/layout/event.rs
@@ -65,7 +65,7 @@ impl<W: WidgetLike<Tag>, Tag> Eventable<W::Widget, Tag> for W {
     fn id_on<E: Event<Ctx>, Ctx>(
         self,
         event: E,
-        mut f: impl Fn(&WidgetId<W::Widget>, &mut Ctx, E::Data) + 'static,
+        f: impl Fn(&WidgetId<W::Widget>, &mut Ctx, E::Data) + 'static,
     ) -> impl WidgetIdFn<W::Widget>
     where
         W::Widget: Widget,
@@ -79,7 +79,7 @@ impl<W: WidgetLike<Tag>, Tag> Eventable<W::Widget, Tag> for W {
     fn edit_on<E: Event<Ui>>(
         self,
         event: E,
-        mut f: impl Fn(&mut W::Widget, E::Data) + 'static,
+        f: impl Fn(&mut W::Widget, E::Data) + 'static,
     ) -> impl WidgetIdFn<W::Widget>
     where
         W::Widget: Widget,
@@ -100,7 +100,7 @@ impl<E: DefaultEvent, Ctx: 'static> Event<Ctx> for E {
 pub trait EventModule<E: Event<Ctx>, Ctx>: UiModule + Default {
     fn register(&mut self, id: Id, event: E, f: impl EventFn<Ctx, E::Data>);
     fn run<'a>(
-        &mut self,
+        &self,
         id: &Id,
         event: E,
     ) -> Option<impl Fn(&mut Ctx, E::Data) + use<'a, Self, E, Ctx>>;
@@ -132,12 +132,8 @@ impl<E: HashableEvent<Ctx>, Ctx: 'static> EventModule<E, Ctx> for DefaultEventMo
             .push(Rc::new(f));
     }
 
-    fn run<'a>(
-        &mut self,
-        id: &Id,
-        event: E,
-    ) -> Option<impl Fn(&mut Ctx, E::Data) + use<'a, E, Ctx>> {
-        if let Some(map) = self.map.get_mut(&event)
+    fn run<'a>(&self, id: &Id, event: E) -> Option<impl Fn(&mut Ctx, E::Data) + use<'a, E, Ctx>> {
+        if let Some(map) = self.map.get(&event)
             && let Some(fs) = map.get(id)
         {
             let fs = fs.clone();
@@ -153,31 +149,18 @@ impl<E: HashableEvent<Ctx>, Ctx: 'static> EventModule<E, Ctx> for DefaultEventMo
 }
 
 impl<E: HashableEvent<Ctx>, Ctx: 'static> DefaultEventModule<E, Ctx> {
-    pub fn run_all(&mut self, ctx: &mut Ctx, event: E, data: E::Data)
+    pub fn run_all(&self, ctx: &mut Ctx, event: E, data: E::Data)
     where
         E::Data: Clone,
     {
-        if let Some(map) = self.map.get_mut(&event) {
-            for fs in map.values_mut() {
+        if let Some(map) = self.map.get(&event) {
+            for fs in map.values() {
                 for f in fs {
                     f(ctx, data.clone())
                 }
             }
         }
     }
-
-    pub fn run<W>(&mut self, ctx: &mut Ctx, id: WidgetId<W>, event: E, data: E::Data)
-    where
-        E::Data: Clone,
-    {
-        if let Some(map) = self.map.get_mut(&event)
-            && let Some(fs) = map.get_mut(&id.id)
-        {
-            for f in fs {
-                f(ctx, data.clone())
-            }
-        }
-    }
 }
 
 impl<E: Event<Ctx> + 'static, Ctx: 'static> Default for DefaultEventModule<E, Ctx> {