diff --git a/apps/sandbox/src/main.rs b/apps/sandbox/src/main.rs
index 9ec1f57..5b54f7b 100644
--- a/apps/sandbox/src/main.rs
+++ b/apps/sandbox/src/main.rs
@@ -33,6 +33,7 @@ struct App {
     last_update: Instant,
     protocol_buf: String,
     bind_message_buf: String,
+    panel_bg: egui::Color32,
 }
 
 impl App {
@@ -49,6 +50,7 @@ impl App {
             last_update: Instant::now(),
             protocol_buf: String::new(),
             bind_message_buf: String::new(),
+            panel_bg: egui::Color32::TRANSPARENT,
         }
     }
 }
@@ -58,6 +60,8 @@ impl eframe::App for App {
         ctx.request_repaint();
 
         egui::SidePanel::left("left_panel").show(ctx, |ui| {
+            ui.heading("New Panel");
+
             ui.label("Protocol name:");
             ui.text_edit_singleline(&mut self.protocol_buf);
 
@@ -81,6 +85,14 @@ impl eframe::App for App {
 
                 self.panels.push(panel);
             }
+
+            ui.separator();
+            ui.heading("Global Settings");
+
+            ui.horizontal(|ui| {
+                ui.label("Panel background color: ");
+                ui.color_edit_button_srgba(&mut self.panel_bg);
+            });
         });
 
         let dt = self.last_update.elapsed().as_secs_f32();
@@ -88,7 +100,7 @@ impl eframe::App for App {
 
         for panel in self.panels.iter_mut() {
             panel.panel.update(dt);
-            panel.show(ctx);
+            panel.show(self.panel_bg, ctx);
         }
     }
 }
@@ -102,83 +114,87 @@ pub struct PanelWindow {
 }
 
 impl PanelWindow {
-    pub fn show(&mut self, ctx: &egui::Context) {
+    pub fn show(&mut self, bg: egui::Color32, ctx: &egui::Context) {
+        let frame = egui::Frame::window(&ctx.style()).fill(bg);
         let window_id = egui::Id::new(format!("panel_{}", self.index));
-        egui::Window::new("Panel").id(window_id).show(ctx, |ui| {
-            egui::menu::bar(ui, |ui| {
-                ui.checkbox(&mut self.show_msg, "Show Message Editor");
-            });
+        egui::Window::new("Panel")
+            .frame(frame)
+            .id(window_id)
+            .show(ctx, |ui| {
+                egui::menu::bar(ui, |ui| {
+                    ui.checkbox(&mut self.show_msg, "Show Message Editor");
+                });
 
-            let sense = egui::Sense {
-                click: true,
-                drag: true,
-                focusable: true,
-            };
-
-            let desired_size = ui.available_size();
-            let response = ui.allocate_response(desired_size, sense);
-            let rect = response.rect;
-
-            if rect.size() != self.current_size {
-                let size = rect.size();
-                self.current_size = size;
-
-                let size = canary::Vec2::new(size.x, size.y);
-                self.panel.on_resize(size * PX_PER_MM);
-            }
-
-            if let Some(hover_pos) = response.hover_pos() {
-                let local = (hover_pos - rect.left_top()) * PX_PER_MM;
-                let pos = canary::Vec2::new(local.x, local.y);
-
-                let kind = if response.drag_started() {
-                    CursorEventKind::Select
-                } else if response.drag_released() {
-                    CursorEventKind::Deselect
-                } else if response.dragged() {
-                    CursorEventKind::Drag
-                } else {
-                    CursorEventKind::Hover
+                let sense = egui::Sense {
+                    click: true,
+                    drag: true,
+                    focusable: true,
                 };
 
-                self.panel.on_cursor_event(kind, pos);
-            }
+                let desired_size = ui.available_size();
+                let response = ui.allocate_response(desired_size, sense);
+                let rect = response.rect;
 
-            let texture = egui::TextureId::Managed(0);
-            let uv = egui::pos2(0.0, 0.0);
-            let mut mesh = egui::Mesh::with_texture(texture);
+                if rect.size() != self.current_size {
+                    let size = rect.size();
+                    self.current_size = size;
 
-            let commands = self.panel.draw();
-            for command in commands.into_iter() {
-                let voff = mesh.vertices.len() as u32;
-
-                match command {
-                    canary::DrawCommand::Mesh { vertices, indices } => {
-                        for v in vertices.iter() {
-                            use egui::epaint::Vertex;
-                            let pos = v.position / PX_PER_MM;
-                            let pos = egui::pos2(pos.x, pos.y);
-                            let pos = pos + rect.left_top().to_vec2();
-                            let (r, g, b, a) = v.color.to_rgba_unmultiplied();
-                            let color = egui::Color32::from_rgba_unmultiplied(r, g, b, a);
-                            let v = Vertex { pos, uv, color };
-                            mesh.vertices.push(v);
-                        }
-
-                        for i in indices.iter() {
-                            mesh.indices.push(i + voff);
-                        }
-                    }
-                    _ => unimplemented!(),
+                    let size = canary::Vec2::new(size.x, size.y);
+                    self.panel.on_resize(size * PX_PER_MM);
                 }
-            }
 
-            let painter = ui.painter_at(rect);
-            let shape = egui::Shape::mesh(mesh);
-            painter.add(shape);
+                if let Some(hover_pos) = response.hover_pos() {
+                    let local = (hover_pos - rect.left_top()) * PX_PER_MM;
+                    let pos = canary::Vec2::new(local.x, local.y);
 
-            response
-        });
+                    let kind = if response.drag_started() {
+                        CursorEventKind::Select
+                    } else if response.drag_released() {
+                        CursorEventKind::Deselect
+                    } else if response.dragged() {
+                        CursorEventKind::Drag
+                    } else {
+                        CursorEventKind::Hover
+                    };
+
+                    self.panel.on_cursor_event(kind, pos);
+                }
+
+                let texture = egui::TextureId::Managed(0);
+                let uv = egui::pos2(0.0, 0.0);
+                let mut mesh = egui::Mesh::with_texture(texture);
+
+                let commands = self.panel.draw();
+                for command in commands.into_iter() {
+                    let voff = mesh.vertices.len() as u32;
+
+                    match command {
+                        canary::DrawCommand::Mesh { vertices, indices } => {
+                            for v in vertices.iter() {
+                                use egui::epaint::Vertex;
+                                let pos = v.position / PX_PER_MM;
+                                let pos = egui::pos2(pos.x, pos.y);
+                                let pos = pos + rect.left_top().to_vec2();
+                                let (r, g, b, a) = v.color.to_rgba_unmultiplied();
+                                let color = egui::Color32::from_rgba_unmultiplied(r, g, b, a);
+                                let v = Vertex { pos, uv, color };
+                                mesh.vertices.push(v);
+                            }
+
+                            for i in indices.iter() {
+                                mesh.indices.push(i + voff);
+                            }
+                        }
+                        _ => unimplemented!(),
+                    }
+                }
+
+                let painter = ui.painter_at(rect);
+                let shape = egui::Shape::mesh(mesh);
+                painter.add(shape);
+
+                response
+            });
 
         let msg_edit_id = egui::Id::new(format!("msg_edit_{}", self.index));
         egui::Window::new("Message Editor")