diff --git a/MainWindow.glade b/MainWindow.glade
index 596f633..21f1c8a 100644
--- a/MainWindow.glade
+++ b/MainWindow.glade
@@ -3,6 +3,8 @@
 <interface>
   <requires lib="gtk+" version="3.24"/>
   <template class="main_window" parent="GtkApplicationWindow">
+    <property name="width-request">800</property>
+    <property name="height-request">500</property>
     <property name="can-focus">False</property>
     <property name="title" translatable="yes">PDF Table Extractor</property>
     <property name="icon-name">document-page-setup</property>
diff --git a/pdf_table_extractor.py b/pdf_table_extractor.py
index 8f32663..6e8ce90 100644
--- a/pdf_table_extractor.py
+++ b/pdf_table_extractor.py
@@ -19,42 +19,88 @@ Coords: TypeAlias = Tuple[float, float]
 class Selection:
     def __init__(self, bounds: Tuple[Coords, Coords], columns: Optional[Sequence[float]] = None):
         self.bounds = bounds
-        self.columns = columns
+        self.columns: list[float] = list(columns or [])
 
+class Page:
+    def __init__(self, index: int, raw: fitz.Page):
+        self.index = index
+        self.raw = raw
+        self.selections: list[Selection] = []
 
 class Document:
     def __init__(self, filename: str):
         self.filename = filename
-        self.document = fitz.Document(filename)
-        self.selections: Dict[int, List[Selection]] = {}
+        self.raw = fitz.Document(filename)
+        self.pages = []
+
+        for i, p in enumerate(self.raw.pages()):  # type: ignore
+            page = Page(index=i, raw=p)
+            self.pages.append(page)
 
 
 class PdfPage(Gtk.DrawingArea):
     def __init__(self, page, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
-        self.page: fitz.Page = page
-        pix = self.page.get_pixmap(dpi=96)  # type: ignore
+        self.page: Page = page
+        pix: fitz.Pixmap = self.page.raw.get_pixmap(dpi=96)  # type: ignore
         self.set_size_request(pix.width, pix.height)
-        self.set_app_paintable(True)  # type: ignore
         self.connect("draw", self.on_draw, {})
 
+        if self.page.index == 4:
+            self.page.selections.append(Selection(
+                ((0.1, 0.18), (0.9, 0.72)),
+                columns=[0.08, 0.24, 0.34, 0.42, 0.51, 0.59, 0.67, 0.73, 0.91]
+            ))
+
     def on_draw(self, widget: Gtk.DrawingArea, cr: cairo.Context, data: GObject.GPointer):
-        # app: Application =  widget.get_window().get_application() # type: ignore
         width = widget.get_allocated_width()
         height = widget.get_allocated_height()
 
         sctx = widget.get_style_context()
         Gtk.render_background(sctx, cr, 0, 0, width, height)
 
-        pix = self.page.get_pixmap(dpi=96)  # type: ignore
+        pix: fitz.Pixmap = self.page.raw.get_pixmap(dpi=96)  # type: ignore
         img = PIL.Image.frombytes("RGBA" if pix.alpha else "RGB", [pix.width, pix.height], pix.samples)
         img.putalpha(1)
+        img = PIL.Image.merge("RGBA", (lambda r, g, b, a: (b, g, r, a))(*img.split()))  # type: ignore
         mv: memoryview = memoryview(bytearray(img.tobytes()))
         ims = cairo.ImageSurface.create_for_data(mv, cairo.Format.RGB24, pix.width, pix.height)
         cr.set_source_surface(ims, 0, 0)
         cr.paint()
 
+        for sel in self.page.selections:
+            sel_x1 = sel.bounds[0][0]*pix.width
+            sel_y1 = sel.bounds[0][1]*pix.height
+            sel_x2 = sel.bounds[1][0]*pix.width
+            sel_y2 = sel.bounds[1][1]*pix.height
+
+            # Base settings
+            cr.set_line_cap(cairo.LINE_CAP_BUTT)
+            cr.set_line_width(2)
+
+            # Columns (draw first - below selection)
+            cr.set_dash([5])
+            cr.set_source_rgba(1, 0, 0)
+            for col in sel.columns:
+                col_x = sel_x1 + (sel_x2 - sel_x1) * col
+                cr.move_to(col_x, sel_y1)
+                cr.line_to(col_x, sel_y2)
+                cr.stroke()
+
+            # Selection
+            cr.rectangle(sel_x1, sel_y1, sel_x2 - sel_x1, sel_y2 - sel_y1)
+
+            # White part of the pattern
+            cr.set_source_rgba(1, 1, 1)
+            cr.set_dash([5], 5)
+            cr.stroke_preserve() # important preserve - reuse rectangle
+
+            # Black part of the pattern
+            cr.set_source_rgba(0, 0, 0)
+            cr.set_dash([5])
+            cr.stroke()
+
 
 @Gtk.Template.from_file("MainWindow.glade")
 class MainWindow(Gtk.ApplicationWindow):
@@ -76,8 +122,6 @@ class MainWindow(Gtk.ApplicationWindow):
 
         self.app.connect("notify::document", self.on_document_updated)
 
-        # self.pdf_list_box.add(PdfPage())
-
     # @Gtk.Template.Callback()
     # def example_button_released_cb(self, widget: Gtk.Button, **kwargs):
     #    assert self.example_button == widget
@@ -119,20 +163,35 @@ class MainWindow(Gtk.ApplicationWindow):
     #       editing an existing one won't trigger it
     def on_document_updated(self, recvobj, gparamstring):
         document: Document = self.app.get_property("document")
-        self.header_bar.set_title(document.filename.split("/")[-1])  # type: ignore
-        self.header_bar.set_subtitle(document.filename)  # type: ignore
+        self.header_bar.set_title(document.filename.split("/")[-1])
+        self.header_bar.set_subtitle(document.filename)
 
-        for i in document.document.pages():  # type: ignore
-            row = Gtk.ListBoxRow()
-            page = PdfPage(i)
-            row.add(page)
-            self.pdf_list_box.add(row)  # type: ignore
+        for child in self.pdf_list_box.get_children():
+            if type(child) is Gtk.ListBoxRow:
+                child.destroy()
+
+        for i in document.pages:
+            self.pdf_list_box.add(PdfPage(i))
 
         self.pdf_list_box.show_all()
 
     @Gtk.Template.Callback()
     def on_open_button_small_clicked(self, widget, **kwargs):
-        pass
+        TEST_FILENAME = "/home/luna/Documents/Resources/Praca Licencjacka/sources/2018_Torres-Benitez_Metabolomic analysis Parmotrema.pdf"
+        try:
+            self.app.set_property("document", Document(TEST_FILENAME))
+        except Exception as e:
+            message_dialog = Gtk.MessageDialog(
+                title="An error has occured.",
+                transient_for=self,
+                modal=True,
+                message_type=Gtk.MessageType.ERROR,
+                text=repr(e),
+                secondary_text=traceback.format_exc(),
+                buttons=Gtk.ButtonsType.OK,
+            )
+            message_dialog.run()  # type: ignore
+            message_dialog.destroy()
 
 
 class Application(Gtk.Application):