diff --git a/src/main.rs b/src/main.rs
index f2a272a..70687ee 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,12 +1,12 @@
-// mod window;
+mod ui;
 
-use cairo::Context;
 use clap::Parser;
 use gtk4::prelude::*;
-use gtk4::{Application, ApplicationWindow, DrawingArea};
+use gtk4::Application;
 use std::cell::RefCell;
 use std::path::PathBuf;
 use std::rc::Rc;
+use ui::Ui;
 
 const APP_ID: &str = "de.frajul.music-reader";
 
@@ -19,214 +19,20 @@ struct Cli {
 fn main() {
     let cli = Cli::parse();
     println!("Parse args");
-    let app = Application::builder()
-        .application_id(APP_ID)
-        // .flags(gio::ApplicationFlags::FLAGS_NONE)
-        .build();
+    let app = Application::builder().application_id(APP_ID).build();
 
     app.connect_activate(move |app| {
-        build_ui(&app, &cli);
+        let myui = build_ui(&app);
+        match cli.file.as_ref() {
+            Some(file) => ui::load_document(file, Rc::clone(&myui)),
+            None => {}
+        }
     });
 
     app.run_with_args(&[] as &[&str]);
 }
 
-struct Ui {
-    bottom_bar: gtk4::Box,
-    header_bar: gtk4::HeaderBar,
-    page_indicator: gtk4::Label,
-    drawing_area: gtk4::DrawingArea,
-    drawing_context: Context,
-    document_canvas: Option<DocumentCanvas>,
-}
-
-struct DocumentCanvas {
-    document: poppler::Document,
-    current_page_number: i32,
-    num_pages: i32,
-}
-
-impl DocumentCanvas {
-    pub fn new(document: poppler::Document) -> Self {
-        let num_pages = document.n_pages();
-        DocumentCanvas {
-            document,
-            num_pages,
-            current_page_number: 1,
-        }
-    }
-}
-
-fn toggle_fullscreen(ui: &Ui) {
-    if ui.header_bar.is_visible() {
-        ui.header_bar.hide();
-        ui.bottom_bar.hide();
-    } else {
-        ui.header_bar.show();
-        ui.bottom_bar.show();
-    }
-}
-
-fn update_page_status(ui: &Ui) {
-    let page_status = match &ui.document_canvas {
-        Some(doc) => format!("{} / {}", doc.current_page_number, doc.num_pages),
-        None => "No document loaded!".to_string(),
-    };
-    ui.page_indicator.set_label(page_status.as_str());
-    ui.drawing_area.queue_draw();
-}
-
-fn process_touch(ui: &mut Ui, x: f64, y: f64) {
-    if ui.document_canvas.is_none() {
-        return;
-    }
-
-    let doc = ui.document_canvas.as_mut().unwrap();
-    let center = ui.drawing_area.width() / 2;
-    if y < (ui.drawing_area.height() / 5) as f64 {
-        toggle_fullscreen(ui);
-    } else if x > center as f64 && doc.current_page_number < doc.num_pages {
-        doc.current_page_number += 1;
-    } else if x < center as f64 && doc.current_page_number > 1 {
-        doc.current_page_number -= 1;
-    }
-    update_page_status(ui);
-}
-
-fn draw(ui: &Ui, area: &DrawingArea, context: &Context) {
-    if ui.document_canvas.is_none() {
-        return;
-    }
-    let document_canvas = ui.document_canvas.as_ref().unwrap();
-
-    context.set_source_rgba(1.0, 1.0, 1.0, 1.0);
-    context.paint().unwrap();
-    context.fill().expect("uh oh");
-    context.paint().unwrap();
-
-    let page = document_canvas
-        .document
-        .page(document_canvas.current_page_number - 1)
-        .unwrap();
-    let (w, h) = page.size();
-
-    let width_diff = area.width() as f64 / w;
-    let height_diff = area.height() as f64 / h;
-    context.save().unwrap();
-    if width_diff > height_diff {
-        context.translate(
-            (area.width() as f64 - w * height_diff) / 2.0,
-            (area.height() as f64 - h * height_diff) / 2.0,
-        );
-        context.scale(height_diff, height_diff);
-    } else {
-        context.translate(
-            (area.width() as f64 - w * width_diff) / 2.0,
-            (area.height() as f64 - h * width_diff) / 2.0,
-        );
-        context.scale(width_diff, width_diff);
-    }
-
-    page.render(context);
-
-    let r = ui.drawing_context.paint();
-    match r {
-        Err(v) => println!("Error painting PDF: {v:?}"),
-        Ok(_v) => {}
-    }
-
-    ui.drawing_context.show_page().unwrap();
-}
-
-fn load_document(file: &PathBuf, ui: Rc<RefCell<Ui>>) {
-    println!("Loading file...");
-    // TODO: catch errors
-    let uri = format!("file://{}", file.to_str().unwrap());
-    let document_canvas = DocumentCanvas::new(poppler::Document::from_file(&uri, None).unwrap());
-    ui.borrow_mut().document_canvas = Some(document_canvas);
-
-    update_page_status(&ui.borrow());
-}
-
-fn choose_file(ui: Rc<RefCell<Ui>>, window: &ApplicationWindow) {
-    let filechooser = gtk4::FileChooserDialog::builder()
-        .title("Choose a PDF...")
-        .action(gtk4::FileChooserAction::Open)
-        .modal(true)
-        .build();
-    filechooser.add_button("_Cancel", gtk4::ResponseType::Cancel);
-    filechooser.add_button("_Open", gtk4::ResponseType::Accept);
-    filechooser.set_transient_for(Some(window));
-    filechooser.connect_response(move |d, response| {
-        if response == gtk4::ResponseType::Accept {
-            let path = d.file().unwrap().path().unwrap();
-            load_document(&path, Rc::clone(&ui));
-        }
-        d.destroy();
-    });
-    filechooser.show()
-}
-
-fn build_ui(app: &Application, cli: &Cli) {
-    println!("building ui");
-    let open_file_button = gtk4::Button::from_icon_name("document-open");
-
-    let app_wrapper = gtk4::Box::builder()
-        .orientation(gtk4::Orientation::Vertical)
-        .build();
-
-    let surface = cairo::ImageSurface::create(cairo::Format::Rgb24, 0, 0).unwrap();
-    let ctx = Context::new(&surface).unwrap();
-
-    let ui = Ui {
-        bottom_bar: gtk4::Box::builder().hexpand_set(true).build(),
-        header_bar: gtk4::HeaderBar::builder().build(),
-        page_indicator: gtk4::Label::builder().build(),
-        drawing_area: DrawingArea::builder().hexpand(true).vexpand(true).build(),
-        drawing_context: ctx,
-        document_canvas: None,
-    };
-    let ui = Rc::new(RefCell::new(ui));
-
-    ui.borrow().header_bar.pack_start(&open_file_button);
-    app_wrapper.prepend(&ui.borrow().drawing_area);
-    app_wrapper.append(&ui.borrow().bottom_bar);
-    ui.borrow().bottom_bar.append(&ui.borrow().page_indicator);
-
-    let click = gtk4::GestureClick::new();
-    click.set_button(0);
-    click.connect_pressed(glib::clone!(@weak ui => @default-panic, move |_, _, x, y| {
-    process_touch(&mut ui.borrow_mut(), x, y);
-         }));
-
-    ui.borrow().drawing_area.add_controller(click);
-
-    ui.borrow()
-        .drawing_area
-        .set_draw_func(glib::clone!(@weak ui => move |area, context, _, _| {
-            draw(&ui.borrow(), area, context);
-        }));
-
-    let window = ApplicationWindow::builder()
-        .application(app)
-        .title("Music Reader")
-        .child(&app_wrapper)
-        .maximized(true)
-        .build();
-    let window = Rc::new(RefCell::new(window));
-
-    window.borrow().set_titlebar(Some(&ui.borrow().header_bar));
-
-    match cli.file.as_ref() {
-        Some(file) => load_document(file, Rc::clone(&ui)),
-        None => {}
-    }
-
-    open_file_button.connect_clicked(
-        glib::clone!(@strong window => @default-panic, move |_button| {
-            choose_file(Rc::clone(&ui), &window.borrow());
-        }),
-    );
-
-    window.borrow().present();
+fn build_ui(app: &Application) -> Rc<RefCell<Ui>> {
+    let ui = Ui::build(app);
+    ui
 }
diff --git a/src/ui.rs b/src/ui.rs
new file mode 100644
index 0000000..d440e2a
--- /dev/null
+++ b/src/ui.rs
@@ -0,0 +1,208 @@
+use std::{cell::RefCell, path::PathBuf, rc::Rc};
+
+use cairo::{Context, Format, ImageSurface};
+use gtk4::{
+    prelude::*, Application, ApplicationWindow, Box, Button, DrawingArea, FileChooserAction,
+    FileChooserDialog, HeaderBar, Label, Orientation, ResponseType,
+};
+
+pub struct Ui {
+    bottom_bar: gtk4::Box,
+    header_bar: gtk4::HeaderBar,
+    page_indicator: gtk4::Label,
+    drawing_area: gtk4::DrawingArea,
+    drawing_context: cairo::Context,
+    document_canvas: Option<DocumentCanvas>,
+}
+
+pub struct DocumentCanvas {
+    document: poppler::Document,
+    current_page_number: i32,
+    num_pages: i32,
+}
+
+impl DocumentCanvas {
+    pub fn new(document: poppler::Document) -> Self {
+        let num_pages = document.n_pages();
+        DocumentCanvas {
+            document,
+            num_pages,
+            current_page_number: 1,
+        }
+    }
+}
+
+pub fn toggle_fullscreen(ui: &Ui) {
+    match ui.header_bar.is_visible() {
+        true => {
+            ui.header_bar.hide();
+            ui.bottom_bar.hide();
+        }
+        false => {
+            ui.header_bar.show();
+            ui.bottom_bar.show();
+        }
+    }
+}
+
+fn update_page_status(ui: &Ui) {
+    let page_status = match &ui.document_canvas {
+        Some(doc) => format!("{} / {}", doc.current_page_number, doc.num_pages),
+        None => "No document loaded!".to_string(),
+    };
+    ui.page_indicator.set_label(page_status.as_str());
+    ui.drawing_area.queue_draw();
+}
+
+fn process_touch(ui: &mut Ui, x: f64, y: f64) {
+    if ui.document_canvas.is_none() {
+        return;
+    }
+
+    let doc = ui.document_canvas.as_mut().unwrap();
+    let center = ui.drawing_area.width() / 2;
+    if y < (ui.drawing_area.height() / 5) as f64 {
+        toggle_fullscreen(ui);
+    } else if x > center as f64 && doc.current_page_number < doc.num_pages {
+        doc.current_page_number += 1;
+    } else if x < center as f64 && doc.current_page_number > 1 {
+        doc.current_page_number -= 1;
+    }
+    update_page_status(ui);
+}
+
+fn create_drawing_context() -> Context {
+    let surface = ImageSurface::create(Format::Rgb24, 0, 0).unwrap();
+    Context::new(&surface).unwrap()
+}
+
+impl Ui {
+    pub fn build(app: &Application) -> Rc<RefCell<Ui>> {
+        println!("building ui");
+        let open_file_button = Button::from_icon_name("document-open");
+
+        let app_wrapper = Box::builder().orientation(Orientation::Vertical).build();
+
+        let ui = Ui {
+            bottom_bar: Box::builder().hexpand_set(true).build(),
+            header_bar: HeaderBar::builder().build(),
+            page_indicator: Label::builder().build(),
+            drawing_area: DrawingArea::builder().hexpand(true).vexpand(true).build(),
+            drawing_context: create_drawing_context(),
+            document_canvas: None,
+        };
+        let ui = Rc::new(RefCell::new(ui));
+
+        ui.borrow().header_bar.pack_start(&open_file_button);
+        app_wrapper.prepend(&ui.borrow().drawing_area);
+        app_wrapper.append(&ui.borrow().bottom_bar);
+        ui.borrow().bottom_bar.append(&ui.borrow().page_indicator);
+
+        let click = gtk4::GestureClick::new();
+        click.set_button(0);
+        click.connect_pressed(glib::clone!(@weak ui => @default-panic, move |_, _, x, y| {
+        process_touch(&mut ui.borrow_mut(), x, y);
+             }));
+
+        ui.borrow().drawing_area.add_controller(click);
+
+        ui.borrow().drawing_area.set_draw_func(
+            glib::clone!(@weak ui => move |area, context, _, _| {
+                draw(&ui.borrow(), area, context);
+            }),
+        );
+
+        let window = ApplicationWindow::builder()
+            .application(app)
+            .title("Music Reader")
+            .child(&app_wrapper)
+            .maximized(true)
+            .build();
+        let window = Rc::new(RefCell::new(window));
+
+        window.borrow().set_titlebar(Some(&ui.borrow().header_bar));
+
+        open_file_button.connect_clicked(
+            glib::clone!(@strong ui, @strong window => @default-panic, move |_button| {
+                choose_file(Rc::clone(&ui), &window.borrow());
+            }),
+        );
+
+        window.borrow().present();
+        ui
+    }
+}
+
+fn draw(ui: &Ui, area: &DrawingArea, context: &Context) {
+    if ui.document_canvas.is_none() {
+        return;
+    }
+    let document_canvas = ui.document_canvas.as_ref().unwrap();
+
+    context.set_source_rgba(1.0, 1.0, 1.0, 1.0);
+    context.paint().unwrap();
+    context.fill().expect("uh oh");
+    context.paint().unwrap();
+
+    let page = document_canvas
+        .document
+        .page(document_canvas.current_page_number - 1)
+        .unwrap();
+    let (w, h) = page.size();
+
+    let width_diff = area.width() as f64 / w;
+    let height_diff = area.height() as f64 / h;
+    context.save().unwrap();
+    if width_diff > height_diff {
+        context.translate(
+            (area.width() as f64 - w * height_diff) / 2.0,
+            (area.height() as f64 - h * height_diff) / 2.0,
+        );
+        context.scale(height_diff, height_diff);
+    } else {
+        context.translate(
+            (area.width() as f64 - w * width_diff) / 2.0,
+            (area.height() as f64 - h * width_diff) / 2.0,
+        );
+        context.scale(width_diff, width_diff);
+    }
+
+    page.render(context);
+
+    let r = ui.drawing_context.paint();
+    match r {
+        Err(v) => println!("Error painting PDF: {v:?}"),
+        Ok(_v) => {}
+    }
+
+    ui.drawing_context.show_page().unwrap();
+}
+
+fn choose_file(ui: Rc<RefCell<Ui>>, window: &ApplicationWindow) {
+    let filechooser = FileChooserDialog::builder()
+        .title("Choose a PDF...")
+        .action(FileChooserAction::Open)
+        .modal(true)
+        .build();
+    filechooser.add_button("_Cancel", ResponseType::Cancel);
+    filechooser.add_button("_Open", ResponseType::Accept);
+    filechooser.set_transient_for(Some(window));
+    filechooser.connect_response(move |d, response| {
+        if response == ResponseType::Accept {
+            let path = d.file().unwrap().path().unwrap();
+            load_document(&path, Rc::clone(&ui));
+        }
+        d.destroy();
+    });
+    filechooser.show()
+}
+
+pub fn load_document(file: &PathBuf, ui: Rc<RefCell<Ui>>) {
+    println!("Loading file...");
+    // TODO: catch errors, maybe show error dialog
+    let uri = format!("file://{}", file.to_str().unwrap());
+    let document_canvas = DocumentCanvas::new(poppler::Document::from_file(&uri, None).unwrap());
+    ui.borrow_mut().document_canvas = Some(document_canvas);
+
+    update_page_status(&ui.borrow());
+}