diff --git a/src/bin/topola-egui/app.rs b/src/bin/topola-egui/app.rs
index a782653..f7bccea 100644
--- a/src/bin/topola-egui/app.rs
+++ b/src/bin/topola-egui/app.rs
@@ -1,3 +1,4 @@
+use geo::point;
 use std::{
     future::Future,
     io,
@@ -6,7 +7,10 @@ use std::{
 };
 use unic_langid::{langid, LanguageIdentifier};
 
-use topola::specctra::design::{LoadingError as SpecctraLoadingError, SpecctraDesign};
+use topola::{
+    interactor::activity::InteractiveInput,
+    specctra::design::{LoadingError as SpecctraLoadingError, SpecctraDesign},
+};
 
 use crate::{
     config::Config, error_dialog::ErrorDialog, menu_bar::MenuBar, status_bar::StatusBar,
@@ -62,19 +66,19 @@ impl App {
         this
     }
 
-    fn advance_state_by_dt(&mut self, dt: f32) {
-        self.update_counter += dt;
+    fn advance_state_by_dt(&mut self, interactive_input: &InteractiveInput) {
+        self.update_counter += interactive_input.dt;
 
         while self.update_counter >= self.menu_bar.frame_timestep {
             self.update_counter -= self.menu_bar.frame_timestep;
 
-            if let ControlFlow::Break(()) = self.update_state() {
+            if let ControlFlow::Break(()) = self.update_state(interactive_input) {
                 return;
             }
         }
     }
 
-    fn update_state(&mut self) -> ControlFlow<()> {
+    fn update_state(&mut self, interactive_input: &InteractiveInput) -> ControlFlow<()> {
         if let Ok(data) = self.content_channel.1.try_recv() {
             match data {
                 Ok(design) => match Workspace::new(design, &self.translator) {
@@ -112,7 +116,11 @@ impl App {
         }
 
         if let Some(workspace) = &mut self.maybe_workspace {
-            return workspace.update_state(&self.translator, &mut self.error_dialog);
+            return workspace.update_state(
+                &self.translator,
+                &mut self.error_dialog,
+                interactive_input,
+            );
         }
 
         ControlFlow::Break(())
@@ -135,7 +143,13 @@ impl eframe::App for App {
             self.maybe_workspace.as_mut(),
         );
 
-        self.advance_state_by_dt(ctx.input(|i| i.stable_dt));
+        let pointer_pos = self.viewport.transform.inverse()
+            * ctx.input(|i| i.pointer.latest_pos().unwrap_or_default());
+
+        self.advance_state_by_dt(&InteractiveInput {
+            pointer_pos: point! {x: pointer_pos.x as f64, y: pointer_pos.y as f64},
+            dt: ctx.input(|i| i.stable_dt),
+        });
 
         self.status_bar.update(
             ctx,
diff --git a/src/bin/topola-egui/menu_bar.rs b/src/bin/topola-egui/menu_bar.rs
index b195642..ca63ba3 100644
--- a/src/bin/topola-egui/menu_bar.rs
+++ b/src/bin/topola-egui/menu_bar.rs
@@ -8,10 +8,7 @@ use topola::{
     autorouter::{
         execution::Command, invoker::InvokerError, selection::Selection, AutorouterOptions,
     },
-    interactor::{
-        activity::{ActivityContext, ActivityStepperWithStatus},
-        interaction::InteractionContext,
-    },
+    interactor::activity::{ActivityContext, ActivityStepperWithStatus, InteractiveInput},
     router::RouterOptions,
     specctra::design::{LoadingError as SpecctraLoadingError, SpecctraDesign},
     stepper::Abort,
@@ -277,7 +274,7 @@ impl MenuBar {
                     } else if actions.edit.redo.consume_key_triggered(ctx, ui) {
                         workspace.interactor.redo();
                     } else if actions.edit.abort.consume_key_triggered(ctx, ui) {
-                        workspace.interactor.abort()
+                        workspace.interactor.abort();
                     } else if actions.place.place_via.consume_key_enabled(
                         ctx,
                         ui,
diff --git a/src/bin/topola-egui/workspace.rs b/src/bin/topola-egui/workspace.rs
index 5a07372..8d5e94d 100644
--- a/src/bin/topola-egui/workspace.rs
+++ b/src/bin/topola-egui/workspace.rs
@@ -6,8 +6,7 @@ use std::{
 use topola::{
     autorouter::{history::History, invoker::Invoker, Autorouter},
     interactor::{
-        activity::{ActivityContext, ActivityStepperWithStatus},
-        interaction::InteractionContext,
+        activity::{ActivityContext, ActivityStepperWithStatus, InteractiveInput},
         Interactor,
     },
     specctra::{design::SpecctraDesign, mesadata::SpecctraMesadata},
@@ -59,6 +58,7 @@ impl Workspace {
         &mut self,
         tr: &Translator,
         error_dialog: &mut ErrorDialog,
+        interactive_input: &InteractiveInput,
     ) -> ControlFlow<()> {
         if let Ok(data) = self.history_channel.1.try_recv() {
             match data {
@@ -84,7 +84,7 @@ impl Workspace {
             }
         }
 
-        match self.interactor.update() {
+        match self.interactor.update(interactive_input) {
             ControlFlow::Continue(()) => ControlFlow::Continue(()),
             ControlFlow::Break(Ok(())) => ControlFlow::Break(()),
             ControlFlow::Break(Err(err)) => {
diff --git a/src/interactor/activity.rs b/src/interactor/activity.rs
index ad1b65b..fb72eed 100644
--- a/src/interactor/activity.rs
+++ b/src/interactor/activity.rs
@@ -1,5 +1,6 @@
 use std::ops::ControlFlow;
 
+use geo::Point;
 use thiserror::Error;
 
 use crate::{
@@ -12,13 +13,18 @@ use crate::{
     board::mesadata::AccessMesadata,
     drawing::graph::PrimitiveIndex,
     geometry::primitive::PrimitiveShape,
-    interactor::interaction::{InteractionContext, InteractionError, InteractionStepper},
+    interactor::interaction::{InteractionError, InteractionStepper},
     router::{navcord::NavcordStepper, navmesh::Navmesh},
     stepper::{Abort, Step},
 };
 
+pub struct InteractiveInput {
+    pub pointer_pos: Point,
+    pub dt: f32,
+}
+
 pub struct ActivityContext<'a, M: AccessMesadata> {
-    pub interaction: InteractionContext,
+    pub interactive_input: &'a InteractiveInput,
     pub invoker: &'a mut Invoker<M>,
 }
 
@@ -43,9 +49,7 @@ impl<M: AccessMesadata> Step<ActivityContext<'_, M>, String> for ActivityStepper
         context: &mut ActivityContext<M>,
     ) -> Result<ControlFlow<String>, ActivityError> {
         match self {
-            ActivityStepper::Interaction(interaction) => {
-                Ok(interaction.step(&mut context.interaction)?)
-            }
+            ActivityStepper::Interaction(interaction) => Ok(interaction.step(context)?),
             ActivityStepper::Execution(execution) => Ok(execution.step(context.invoker)?),
         }
     }
@@ -54,9 +58,7 @@ impl<M: AccessMesadata> Step<ActivityContext<'_, M>, String> for ActivityStepper
 impl<M: AccessMesadata> Abort<ActivityContext<'_, M>> for ActivityStepper {
     fn abort(&mut self, context: &mut ActivityContext<M>) {
         match self {
-            ActivityStepper::Interaction(interaction) => {
-                interaction.abort(&mut context.interaction)
-            }
+            ActivityStepper::Interaction(interaction) => interaction.abort(context),
             ActivityStepper::Execution(execution) => {
                 execution.finish(context.invoker);
             } // TODO.
diff --git a/src/interactor/interaction.rs b/src/interactor/interaction.rs
index 5e8d9dd..0ee5ce2 100644
--- a/src/interactor/interaction.rs
+++ b/src/interactor/interaction.rs
@@ -4,17 +4,14 @@ use thiserror::Error;
 
 use crate::{
     autorouter::invoker::{GetGhosts, GetMaybeNavcord, GetMaybeNavmesh, GetObstacles},
+    board::mesadata::AccessMesadata,
     drawing::graph::PrimitiveIndex,
     geometry::primitive::PrimitiveShape,
     router::{navcord::NavcordStepper, navmesh::Navmesh},
     stepper::{Abort, Step},
 };
 
-pub struct InteractionContext {
-    // Empty for now.
-    // For example, this will contain mouse pointer position.
-    // (we will need an additional struct to hold a reference to a `Board<...>`)
-}
+use super::activity::ActivityContext;
 
 #[derive(Error, Debug, Clone)]
 pub enum InteractionError {
@@ -29,19 +26,19 @@ pub enum InteractionStepper {
     // - interactively moving a footprint.
 }
 
-impl Step<InteractionContext, String> for InteractionStepper {
+impl<'a, M: AccessMesadata> Step<ActivityContext<'a, M>, String> for InteractionStepper {
     type Error = InteractionError;
 
     fn step(
         &mut self,
-        context: &mut InteractionContext,
+        context: &mut ActivityContext<M>,
     ) -> Result<ControlFlow<String>, InteractionError> {
         Ok(ControlFlow::Break(String::from("")))
     }
 }
 
-impl Abort<InteractionContext> for InteractionStepper {
-    fn abort(&mut self, context: &mut InteractionContext) {
+impl<'a, M: AccessMesadata> Abort<ActivityContext<'a, M>> for InteractionStepper {
+    fn abort(&mut self, context: &mut ActivityContext<M>) {
         todo!();
     }
 }
diff --git a/src/interactor/interactor.rs b/src/interactor/interactor.rs
index 2c0f372..6f04bfb 100644
--- a/src/interactor/interactor.rs
+++ b/src/interactor/interactor.rs
@@ -10,9 +10,8 @@ use crate::{
         Autorouter,
     },
     board::{mesadata::AccessMesadata, Board},
-    interactor::{
-        activity::{ActivityContext, ActivityError, ActivityStepperWithStatus},
-        interaction::InteractionContext,
+    interactor::activity::{
+        ActivityContext, ActivityError, ActivityStepperWithStatus, InteractiveInput,
     },
     stepper::{Abort, Step},
 };
@@ -51,8 +50,11 @@ impl<M: AccessMesadata> Interactor<M> {
 
     pub fn abort(&mut self) {
         if let Some(ref mut activity) = self.activity {
-            activity.abort(&mut ActivityContext {
-                interaction: InteractionContext {},
+            activity.abort(&mut ActivityContext::<M> {
+                interactive_input: &InteractiveInput {
+                    pointer_pos: [0.0, 0.0].into(),
+                    dt: 0.0,
+                },
                 invoker: &mut self.invoker,
             });
         }
@@ -62,10 +64,13 @@ impl<M: AccessMesadata> Interactor<M> {
         self.invoker.replay(history);
     }
 
-    pub fn update(&mut self) -> ControlFlow<Result<(), ActivityError>> {
+    pub fn update(
+        &mut self,
+        interactive_input: &InteractiveInput,
+    ) -> ControlFlow<Result<(), ActivityError>> {
         if let Some(ref mut activity) = self.activity {
             return match activity.step(&mut ActivityContext {
-                interaction: InteractionContext {},
+                interactive_input,
                 invoker: &mut self.invoker,
             }) {
                 Ok(ControlFlow::Continue(())) => ControlFlow::Continue(()),