diff --git a/Cargo.lock b/Cargo.lock
index 404aba1e..86ca1f2a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2551,7 +2551,6 @@ name = "tek_test"
 version = "0.1.0"
 dependencies = [
  "tek_core",
- "tek_mixer",
  "tek_sequencer",
 ]
 
diff --git a/crates/tek_core/src/engine/collect.rs b/crates/tek_core/src/engine/collect.rs
index 1d912773..7da4d05d 100644
--- a/crates/tek_core/src/engine/collect.rs
+++ b/crates/tek_core/src/engine/collect.rs
@@ -52,7 +52,7 @@ impl<'a, E: Engine> Collect<'a, E> for Collection<'a, E> {
     }
 }
 
-pub struct Layers<'a, E: Engine>(pub &'a [&'a dyn Widget<Engine = E>]);
+pub struct Layers<'a, E: Engine, const N: usize>(pub [&'a dyn Widget<Engine = E>;N]);
 
 // this actually works, except for the type inference
 //pub struct Layers<'a, E: Engine + 'a, I: std::iter::IntoIterator<Item = &'a dyn Render<E>>>(
diff --git a/crates/tek_core/src/engine/component.rs b/crates/tek_core/src/engine/component.rs
index adb76b43..1198261d 100644
--- a/crates/tek_core/src/engine/component.rs
+++ b/crates/tek_core/src/engine/component.rs
@@ -1,6 +1,6 @@
 use crate::*;
 
-pub trait Widget {
+pub trait Widget: Send + Sync {
     type Engine: Engine;
     fn layout (&self, to: <<Self as Widget>::Engine as Engine>::Area) ->
         Perhaps<<<Self as Widget>::Engine as Engine>::Area>;
@@ -71,7 +71,7 @@ impl<E: Engine, W: Widget<Engine = E>> Widget for Option<W> {
     }
 }
 
-pub trait Content {
+pub trait Content: Send + Sync {
     type Engine: Engine;
     fn content (&self) -> impl Widget<Engine = <Self as Content>::Engine>;
 }
diff --git a/crates/tek_core/src/tui/tui_layout.rs b/crates/tek_core/src/tui/tui_layout.rs
index 6a33a606..98164271 100644
--- a/crates/tek_core/src/tui/tui_layout.rs
+++ b/crates/tek_core/src/tui/tui_layout.rs
@@ -53,7 +53,7 @@ impl<'a> Split<'a, Tui> {
     }
 }
 
-impl<'a> Widget for Layers<'a, Tui> {
+impl<'a, const N: usize> Widget for Layers<'a, Tui, N> {
     type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         let [x, y, ..] = area;
diff --git a/crates/tek_mixer/src/lib.rs b/crates/tek_mixer/src/lib.rs
index 8d1f5dd4..411a172d 100644
--- a/crates/tek_mixer/src/lib.rs
+++ b/crates/tek_mixer/src/lib.rs
@@ -13,19 +13,21 @@ submod! {
     mixer
     mixer_cli
     mixer_handle
-    track
-    track_view
-    track_handle
     plugin
+    plugin_handle
     plugin_lv2
     plugin_lv2_gui
+    plugin_view
     plugin_vst2
     plugin_vst3
     sample
     sample_add
     sampler
     sampler_edn
-    sampler_view
     sampler_handle
+    sampler_view
+    track
+    track_handle
+    track_view
     voice
 }
diff --git a/crates/tek_mixer/src/plugin.rs b/crates/tek_mixer/src/plugin.rs
index f1f15a47..5b014c6c 100644
--- a/crates/tek_mixer/src/plugin.rs
+++ b/crates/tek_mixer/src/plugin.rs
@@ -1,7 +1,8 @@
 use crate::*;
 
 /// A plugin device.
-pub struct Plugin {
+pub struct Plugin<E> {
+    _engine:      PhantomData<E>,
     pub name:     String,
     pub path:     Option<String>,
     pub plugin:   Option<PluginKind>,
@@ -9,63 +10,13 @@ pub struct Plugin {
     pub mapping:  bool,
     pub ports:    JackPorts,
 }
-impl Handle<Tui> for Plugin {
-    fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
-        handle_keymap(self, &from.event(), KEYMAP_PLUGIN).map(|x|Some(x))
-    }
-}
-process!(Plugin = Plugin::process);
-impl Render<Tui> for Plugin {
-    fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
-        let area = to.area();
-        let [x, y, _, height] = area;
-        let mut width = 20u16;
-        match &self.plugin {
-            Some(PluginKind::LV2(LV2Plugin { port_list, instance, .. })) => {
-                let start = self.selected.saturating_sub((height as usize / 2).saturating_sub(1));
-                let end   = start + height as usize - 2;
-                //draw_box(buf, Rect { x, y, width, height });
-                for i in start..end {
-                    if let Some(port) = port_list.get(i) {
-                        let value = if let Some(value) = instance.control_input(port.index) {
-                            value
-                        } else {
-                            port.default_value
-                        };
-                        //let label = &format!("C·· M·· {:25} = {value:.03}", port.name);
-                        let label = &format!("{:25} = {value:.03}", port.name);
-                        width = width.max(label.len() as u16 + 4);
-                        let style = if i == self.selected {
-                            Some(Style::default().green())
-                        } else {
-                            None
-                        } ;
-                        to.blit(&label, x + 2, y + 1 + i as u16 - start as u16, style)?;
-                    } else {
-                        break
-                    }
-                }
-            },
-            _ => {}
-        };
-        draw_header(self, to, x, y, width)?;
-        Ok(Some([x, y, width, height]))
-    }
-}
 
-/// Supported plugin formats.
-pub enum PluginKind {
-    LV2(LV2Plugin),
-    VST2 {
-        instance: ::vst::host::PluginInstance
-    },
-    VST3,
-}
-impl Plugin {
+impl<E> Plugin<E> {
     pub fn new_lv2 (name: &str, path: &str) -> Usually<JackDevice<Tui>> {
         let plugin = LV2Plugin::new(path)?;
         jack_from_lv2(name, &plugin.plugin)?
             .run(|ports|Box::new(Self {
+                _engine:    Default::default(),
                 name:       name.into(),
                 path:       Some(String::from(path)),
                 plugin:     Some(PluginKind::LV2(plugin)),
@@ -77,6 +28,7 @@ impl Plugin {
     /// Create a plugin host device.
     pub fn new (name: &str) -> Usually<Self> {
         Ok(Self {
+            _engine:    Default::default(),
             name:       name.into(),
             path:       None,
             plugin:     None,
@@ -85,7 +37,10 @@ impl Plugin {
             ports:      JackPorts::default()
         })
     }
-    pub fn process (&mut self, _: &Client, scope: &ProcessScope) -> Control {
+}
+
+impl<E> Process for Plugin<E> {
+    fn process (&mut self, _: &Client, scope: &ProcessScope) -> Control {
         match self.plugin.as_mut() {
             Some(PluginKind::LV2(LV2Plugin {
                 features,
@@ -141,79 +96,12 @@ impl Plugin {
         Control::Continue
     }
 }
-fn draw_header (state: &Plugin, to: &mut Tui, x: u16, y: u16, w: u16) -> Usually<Rect> {
-    let style  = Style::default().gray();
-    let label1 = format!(" {}", state.name);
-    to.blit(&label1, x + 1, y, Some(style.white().bold()))?;
-    if let Some(ref path) = state.path {
-        let label2 = format!("{}…", &path[..((w as usize - 10).min(path.len()))]);
-        to.blit(&label2, x + 2 + label1.len() as u16, y, Some(style.not_dim()))?;
-    }
-    Ok(Rect { x, y, width: w, height: 1 })
-}
 
-/// Key bindings for plugin device.
-pub const KEYMAP_PLUGIN: &'static [KeyBinding<Plugin>] = keymap!(Plugin {
-    [Up,        NONE, "/plugin/cursor_up",   "move cursor up",   |s: &mut Plugin|{
-        s.selected = s.selected.saturating_sub(1);
-        Ok(true)
-    }],
-    [Down,      NONE, "/plugin/cursor_down", "move cursor down", |s: &mut Plugin|{
-        s.selected = (s.selected + 1).min(match &s.plugin {
-            Some(PluginKind::LV2(LV2Plugin { port_list, .. })) => port_list.len() - 1,
-            _ => unimplemented!()
-        });
-        Ok(true)
-    }],
-    [PageUp,    NONE, "/plugin/cursor_page_up",   "move cursor up",   |s: &mut Plugin|{
-        s.selected = s.selected.saturating_sub(8);
-        Ok(true)
-    }],
-    [PageDown,  NONE, "/plugin/cursor_page_down", "move cursor down", |s: &mut Plugin|{
-        s.selected = (s.selected + 10).min(match &s.plugin {
-            Some(PluginKind::LV2(LV2Plugin { port_list, .. })) => port_list.len() - 1,
-            _ => unimplemented!()
-        });
-        Ok(true)
-    }],
-    [Char(','), NONE, "/plugin/decrement",   "decrement value",  |s: &mut Plugin|{
-        match s.plugin.as_mut() {
-            Some(PluginKind::LV2(LV2Plugin { port_list, ref mut instance, .. })) => {
-                let index = port_list[s.selected].index;
-                if let Some(value) = instance.control_input(index) {
-                    instance.set_control_input(index, value - 0.01);
-                }
-            },
-            _ => {}
-        }
-        Ok(true)
-    }],
-    [Char('.'), NONE, "/plugin/decrement",   "increment value",  |s: &mut Plugin|{
-        match s.plugin.as_mut() {
-            Some(PluginKind::LV2(LV2Plugin { port_list, ref mut instance, .. })) => {
-                let index = port_list[s.selected].index;
-                if let Some(value) = instance.control_input(index) {
-                    instance.set_control_input(index, value + 0.01);
-                }
-            },
-            _ => {}
-        }
-        Ok(true)
-    }],
-    [Char('g'), NONE, "/plugin/gui_toggle", "toggle plugin UI", |s: &mut Plugin|{
-        match s.plugin {
-            Some(PluginKind::LV2(ref mut plugin)) => {
-                plugin.ui_thread = Some(run_lv2_ui(LV2PluginUI::new()?)?);
-            },
-            Some(_) => unreachable!(),
-            None => {}
-        }
-        Ok(true)
-    }],
-});
-
-impl Layout<Tui> for Plugin {
-    fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
-        todo!()
-    }
+/// Supported plugin formats.
+pub enum PluginKind {
+    LV2(LV2Plugin),
+    VST2 {
+        instance: ::vst::host::PluginInstance
+    },
+    VST3,
 }
diff --git a/crates/tek_mixer/src/plugin_handle.rs b/crates/tek_mixer/src/plugin_handle.rs
new file mode 100644
index 00000000..6f5a1e0a
--- /dev/null
+++ b/crates/tek_mixer/src/plugin_handle.rs
@@ -0,0 +1,67 @@
+use crate::*;
+
+impl Handle<Tui> for Plugin<Tui> {
+    fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
+        handle_keymap(self, &from.event(), KEYMAP_PLUGIN).map(|x|Some(x))
+    }
+}
+
+/// Key bindings for plugin device.
+pub const KEYMAP_PLUGIN: &'static [KeyBinding<Plugin>] = keymap!(Plugin {
+    [Up,        NONE, "/plugin/cursor_up",   "move cursor up",   |s: &mut Plugin|{
+        s.selected = s.selected.saturating_sub(1);
+        Ok(true)
+    }],
+    [Down,      NONE, "/plugin/cursor_down", "move cursor down", |s: &mut Plugin|{
+        s.selected = (s.selected + 1).min(match &s.plugin {
+            Some(PluginKind::LV2(LV2Plugin { port_list, .. })) => port_list.len() - 1,
+            _ => unimplemented!()
+        });
+        Ok(true)
+    }],
+    [PageUp,    NONE, "/plugin/cursor_page_up",   "move cursor up",   |s: &mut Plugin|{
+        s.selected = s.selected.saturating_sub(8);
+        Ok(true)
+    }],
+    [PageDown,  NONE, "/plugin/cursor_page_down", "move cursor down", |s: &mut Plugin|{
+        s.selected = (s.selected + 10).min(match &s.plugin {
+            Some(PluginKind::LV2(LV2Plugin { port_list, .. })) => port_list.len() - 1,
+            _ => unimplemented!()
+        });
+        Ok(true)
+    }],
+    [Char(','), NONE, "/plugin/decrement",   "decrement value",  |s: &mut Plugin|{
+        match s.plugin.as_mut() {
+            Some(PluginKind::LV2(LV2Plugin { port_list, ref mut instance, .. })) => {
+                let index = port_list[s.selected].index;
+                if let Some(value) = instance.control_input(index) {
+                    instance.set_control_input(index, value - 0.01);
+                }
+            },
+            _ => {}
+        }
+        Ok(true)
+    }],
+    [Char('.'), NONE, "/plugin/decrement",   "increment value",  |s: &mut Plugin|{
+        match s.plugin.as_mut() {
+            Some(PluginKind::LV2(LV2Plugin { port_list, ref mut instance, .. })) => {
+                let index = port_list[s.selected].index;
+                if let Some(value) = instance.control_input(index) {
+                    instance.set_control_input(index, value + 0.01);
+                }
+            },
+            _ => {}
+        }
+        Ok(true)
+    }],
+    [Char('g'), NONE, "/plugin/gui_toggle", "toggle plugin UI", |s: &mut Plugin|{
+        match s.plugin {
+            Some(PluginKind::LV2(ref mut plugin)) => {
+                plugin.ui_thread = Some(run_lv2_ui(LV2PluginUI::new()?)?);
+            },
+            Some(_) => unreachable!(),
+            None => {}
+        }
+        Ok(true)
+    }],
+});
diff --git a/crates/tek_mixer/src/plugin_view.rs b/crates/tek_mixer/src/plugin_view.rs
new file mode 100644
index 00000000..18529cf8
--- /dev/null
+++ b/crates/tek_mixer/src/plugin_view.rs
@@ -0,0 +1,54 @@
+use crate::*;
+
+impl Widget for Plugin<Tui> {
+    type Engine = Tui;
+    fn layout (&self, to: [u16;4]) -> Perhaps<[u16;4]> {
+        Ok(Some(to))
+    }
+    fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
+        let area = to.area();
+        let [x, y, _, height] = area;
+        let mut width = 20u16;
+        match &self.plugin {
+            Some(PluginKind::LV2(LV2Plugin { port_list, instance, .. })) => {
+                let start = self.selected.saturating_sub((height as usize / 2).saturating_sub(1));
+                let end   = start + height as usize - 2;
+                //draw_box(buf, Rect { x, y, width, height });
+                for i in start..end {
+                    if let Some(port) = port_list.get(i) {
+                        let value = if let Some(value) = instance.control_input(port.index) {
+                            value
+                        } else {
+                            port.default_value
+                        };
+                        //let label = &format!("C·· M·· {:25} = {value:.03}", port.name);
+                        let label = &format!("{:25} = {value:.03}", port.name);
+                        width = width.max(label.len() as u16 + 4);
+                        let style = if i == self.selected {
+                            Some(Style::default().green())
+                        } else {
+                            None
+                        } ;
+                        to.blit(&label, x + 2, y + 1 + i as u16 - start as u16, style)?;
+                    } else {
+                        break
+                    }
+                }
+            },
+            _ => {}
+        };
+        draw_header(self, to, x, y, width)?;
+        Ok(Some([x, y, width, height]))
+    }
+}
+
+fn draw_header <E> (state: &Plugin<E>, to: &mut Tui, x: u16, y: u16, w: u16) -> Usually<Rect> {
+    let style  = Style::default().gray();
+    let label1 = format!(" {}", state.name);
+    to.blit(&label1, x + 1, y, Some(style.white().bold()))?;
+    if let Some(ref path) = state.path {
+        let label2 = format!("{}…", &path[..((w as usize - 10).min(path.len()))]);
+        to.blit(&label2, x + 2 + label1.len() as u16, y, Some(style.not_dim()))?;
+    }
+    Ok(Rect { x, y, width: w, height: 1 })
+}
diff --git a/crates/tek_sequencer/src/arranger_main.rs b/crates/tek_sequencer/src/arranger_main.rs
index 5bc06855..b87a5a76 100644
--- a/crates/tek_sequencer/src/arranger_main.rs
+++ b/crates/tek_sequencer/src/arranger_main.rs
@@ -9,13 +9,13 @@ pub fn main () -> Usually<()> {
 
 struct ArrangerStandalone<E: Engine> {
     /// Contains all the sequencers.
-    arranger:        Arranger<E>,
+    arranger:       Arranger<E>,
     /// Controls the JACK transport.
-    transport:       Option<TransportToolbar>,
+    transport:      Option<TransportToolbar<E>>,
     /// This allows the sequencer view to be moved or hidden.
-    show_sequencer:  Option<tek_core::Direction>,
+    show_sequencer: Option<tek_core::Direction>,
     /// 
-    focus:           usize,
+    focus:          usize,
 }
 
 #[derive(Debug, Parser)]
@@ -38,7 +38,7 @@ pub struct ArrangerCli {
     scenes: usize,
 }
 
-impl<E: Engine> ArrangerStandalone<E> {
+impl ArrangerStandalone<Tui> {
     pub fn from_args () -> Usually<Self> {
         let args = ArrangerCli::parse();
         let mut arranger = Arranger::new("");
@@ -73,10 +73,15 @@ impl<E: Engine> ArrangerStandalone<E> {
     }
 }
 
-impl Render<Tui> for ArrangerStandalone<Tui> {
+impl Widget for ArrangerStandalone<Tui> {
+    type Engine = Tui;
+    fn layout (&self, to: [u16;4]) -> Perhaps<[u16;4]> {
+        Ok(Some(to))
+    }
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
-        let sequencer = self.arranger.sequencer();
+        let sequencer = self.arranger.sequencer()
+            .map(|t|t as &dyn Widget<Engine = Tui>);
         let result = Split::down()
             .add_ref(&self.transport)
             .add_ref(&self.arranger)
diff --git a/crates/tek_sequencer/src/arranger_view_h.rs b/crates/tek_sequencer/src/arranger_view_h.rs
index fdf47da2..13ba6114 100644
--- a/crates/tek_sequencer/src/arranger_view_h.rs
+++ b/crates/tek_sequencer/src/arranger_view_h.rs
@@ -4,7 +4,7 @@ pub fn draw (state: &Arranger<Tui>, to: &mut Tui) -> Perhaps<[u16;4]> {
     let area = to.area();
     let area = [area.x(), area.y(), area.w(), area.h().min((2 + state.tracks.len() * 2) as u16)];
     let tracks = state.tracks.as_slice();
-    Layers(&[
+    Layers([
         &state.focused.then_some(FillBg(COLOR_BG0)),
         &Split::right()
             .add(TrackNameColumn(tracks, state.selected))
diff --git a/crates/tek_sequencer/src/arranger_view_v.rs b/crates/tek_sequencer/src/arranger_view_v.rs
index 7921f0d4..9a71a777 100644
--- a/crates/tek_sequencer/src/arranger_view_v.rs
+++ b/crates/tek_sequencer/src/arranger_view_v.rs
@@ -38,15 +38,15 @@ pub fn draw <'a, 'b> (
     let offset = 3 + scene_name_max_len(state.scenes.as_ref()) as u16;
     let tracks = state.tracks.as_ref();
     let scenes = state.scenes.as_ref();
-    Layered::new()
+    Layers([
         //.add_ref(&FillBg(Color::Rgb(30, 33, 36)))//COLOR_BG1))//bg_lo(state.focused, state.entered)))
-        .add_ref(&ColumnSeparators(offset, cols))
-        .add_ref(&RowSeparators(rows))
-        .add_ref(&CursorFocus(state.selected, offset, cols, rows))
-        .add_ref(&Split::down()
+        &ColumnSeparators(offset, cols),
+        &RowSeparators(rows),
+        &CursorFocus(state.selected, offset, cols, rows),
+        &Split::down()
             .add_ref(&TracksHeader(offset, cols, tracks))
-            .add_ref(&SceneRows(offset, cols, rows, tracks, scenes)))
-        .render(to)
+            .add_ref(&SceneRows(offset, cols, rows, tracks, scenes))
+    ]).render(to.with_rect(area))
 }
 
 struct ColumnSeparators<'a>(u16, &'a [(usize, usize)]);
diff --git a/crates/tek_sequencer/src/sequencer_view_h.rs b/crates/tek_sequencer/src/sequencer_view_h.rs
index d346eb45..cfef4ad3 100644
--- a/crates/tek_sequencer/src/sequencer_view_h.rs
+++ b/crates/tek_sequencer/src/sequencer_view_h.rs
@@ -15,13 +15,13 @@ impl Sequencer<Tui> {
         let area = [area.x() + 10, area.y(), area.w().saturating_sub(10), area.h().min(66)];
         Lozenge(Style::default().fg(Nord::BG2)).draw(to.with_rect(area))?;
         let area = [area.x() + 1, area.y(), area.w().saturating_sub(1), area.h()];
-        Layered::new()
-            .add_ref(&SequenceKeys(&self))
-            .add_ref(&self.phrase.as_ref().map(|phrase|SequenceTimer(&self, phrase.clone())))
-            .add_ref(&SequenceNotes(&self))
-            .add_ref(&SequenceCursor(&self))
-            .add_ref(&SequenceZoom(&self))
-            .render(to.with_rect(area))?;
+        Layers([
+            &SequenceKeys(&self),
+            &self.phrase.as_ref().map(|phrase|SequenceTimer(&self, phrase.clone())),
+            &SequenceNotes(&self),
+            &SequenceCursor(&self),
+            &SequenceZoom(&self),
+        ]).render(to.with_rect(area))?;
         Ok(())
     }
 
diff --git a/crates/tek_sequencer/src/transport.rs b/crates/tek_sequencer/src/transport.rs
index 2bfa5da6..fcb9d1b4 100644
--- a/crates/tek_sequencer/src/transport.rs
+++ b/crates/tek_sequencer/src/transport.rs
@@ -23,7 +23,7 @@ pub struct TransportToolbar<E: Engine> {
     pub clock:     TransportClock<E>,
 }
 impl<E: Engine> TransportToolbar<E> {
-    pub fn standalone () -> Usually<Arc<RwLock<Self>>> {
+    pub fn standalone () -> Usually<Arc<RwLock<Self>>> where Self: 'static {
         let mut transport = Self::new(None);
         transport.focused = true;
         let jack = JackClient::Inactive(
diff --git a/crates/tek_sequencer/src/transport_view.rs b/crates/tek_sequencer/src/transport_view.rs
index 03bee34c..90343611 100644
--- a/crates/tek_sequencer/src/transport_view.rs
+++ b/crates/tek_sequencer/src/transport_view.rs
@@ -22,7 +22,7 @@ impl Widget for TransportPlayPauseButton<Tui> {
     }
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let Self { value, focused, .. } = &self;
-        Layers(&[
+        Layers([
             &focused.then_some(CORNERS),
             &Inset::W(1, Styled(match value {
                 Some(TransportState::Stopped)  => Some(GRAY_DIM.bold()),
diff --git a/crates/tek_test/Cargo.toml b/crates/tek_test/Cargo.toml
index 47ccc134..ba94a840 100644
--- a/crates/tek_test/Cargo.toml
+++ b/crates/tek_test/Cargo.toml
@@ -5,5 +5,5 @@ version = "0.1.0"
 
 [dependencies]
 tek_core = { path = "../tek_core" }
-tek_mixer = { path = "../tek_mixer" }
+#tek_mixer = { path = "../tek_mixer" }
 tek_sequencer = { path = "../tek_sequencer" }
diff --git a/crates/tek_test/src/main.rs b/crates/tek_test/src/main.rs
index af5f21dc..e4baf6ac 100644
--- a/crates/tek_test/src/main.rs
+++ b/crates/tek_test/src/main.rs
@@ -8,17 +8,19 @@ pub fn main () -> Usually<()> {
 
 pub struct Demo<E: Engine> {
     index: usize,
-    items: Vec<Box<dyn Component<E>>>
+    items: Vec<Box<dyn Widget<Engine = E>>>
 }
 
 impl Demo<Tui> {
     fn new () -> Self {
-        let mut items: Vec<Box<dyn Component<Tui>>> = vec![];
+        let mut items: Vec<Box<dyn Widget<Engine = Tui>>> = vec![];
         items.push(Box::new(tek_sequencer::TransportPlayPauseButton {
+            _engine: Default::default(),
             value:   Some(TransportState::Stopped),
             focused: true
         }));
         items.push(Box::new(tek_sequencer::TransportPlayPauseButton {
+            _engine: Default::default(),
             value:   Some(TransportState::Rolling),
             focused: false
         }));
@@ -26,15 +28,16 @@ impl Demo<Tui> {
     }
 }
 
-impl<E: Engine> Content for Demo<E> {
-    type Engine = E;
-    fn content (&self) -> impl Widget<Engine = E> {
-        Align::Center(Layers(&[
+impl Content for Demo<Tui> {
+    type Engine = Tui;
+    fn content (&self) -> impl Widget<Engine = Tui> {
+        Align::Center(Layers([
             &Outset::WH(2, 1, FillBg(Color::Rgb(0,128,128))),
-            &Layers(&[
-                &"---------",
-                &Align::Center("...")
-            ])
+            &self.items[self.index]
+            //&Layers(&[
+                //&"---------",
+                //&Align::Center("...")
+            //])
         ]))
     }
 }