diff --git a/editor/buf.py b/editor/buf.py
deleted file mode 100644
index 42843ad..0000000
--- a/editor/buf.py
+++ /dev/null
@@ -1,65 +0,0 @@
-import sys
-from typing import Optional
-from typing import Sequence
-
-
-class Buffer:
-    MAX_CX = sys.maxsize
-
-    def __init__(
-        self,
-        lines: Optional[Sequence[str]] = None,
-        cx: int = 0,
-        cy: int = 0,
-    ):
-        self._lines = lines or []
-        self.cx = cx
-        self.cy = cy
-
-        self._cx_hint = cx
-
-    def up(self) -> "Buffer":
-        if self.cy > 0:
-            self.cy -= 1
-            self._set_cx_after_vertical_movement()
-        return self
-
-    def down(self) -> "Buffer":
-        if self.cy < len(self._lines) - 1:
-            self.cy += 1
-            self._set_cx_after_vertical_movement()
-        return self
-
-    def _set_cx_after_vertical_movement(self) -> None:
-        if self.cx > self._max_cx:
-            # Cursor exceeded the line
-            if self.cx > self._cx_hint:
-                self._cx_hint = self.cx
-            self.cx = max(self._max_cx, 0)
-        else:
-            self.cx = min(self._cx_hint, self._max_cx)
-
-    def left(self) -> "Buffer":
-        if self.cx > 0:
-            self.cx -= 1
-            self._cx_hint = self.cx
-        return self
-
-    def right(self) -> "Buffer":
-        if self.cx < self._max_cx:
-            self.cx += 1
-            self._cx_hint = self.cx
-        return self
-
-    def home(self) -> "Buffer":
-        self.cx = self._cx_hint = 0
-        return self
-
-    def end(self) -> "Buffer":
-        self._cx_hint = self.MAX_CX
-        self.cx = min(self._cx_hint, self._max_cx)
-        return self
-
-    @property
-    def _max_cx(self) -> int:
-        return len(self._lines[self.cy]) - 1
diff --git a/editor/main.py b/editor/main.py
index cae0c9e..9376d78 100644
--- a/editor/main.py
+++ b/editor/main.py
@@ -3,7 +3,6 @@ import curses
 from typing import Optional
 from typing import Sequence
 
-from .buf import Buffer
 from .window import Window
 
 
@@ -19,30 +18,30 @@ def c_main(stdscr: "curses._CursesWindow", filename: str) -> int:
     with open(filename) as f:
         lines = f.read().split("\n")
 
-    buf = Buffer(lines)
-    window = Window(buf, curses.COLS, curses.LINES)
+    win = Window(lines, curses.COLS, curses.LINES)
 
     while True:
         # Update screen
-        for y, line in enumerate(window.lines):
+        for y, line in enumerate(lines[: curses.LINES]):
             stdscr.addstr(y, 0, line)
-        stdscr.move(window.cy, window.cx)
+        cx, cy = win.screen_cursor()
+        stdscr.move(cy, cx)
 
         # Handle keypresses
         c = stdscr.getkey()
         if c == "q":
             break
         elif c == "k":
-            buf.up()
+            win.up()
         elif c == "j":
-            buf.down()
+            win.down()
         elif c == "h":
-            buf.left()
+            win.left()
         elif c == "l":
-            buf.right()
+            win.right()
         elif c == "0":
-            buf.home()
+            win.home()
         elif c == "$":
-            buf.end()
+            win.end()
 
     return 0
diff --git a/editor/window.py b/editor/window.py
index 9e74c56..d81c330 100644
--- a/editor/window.py
+++ b/editor/window.py
@@ -1,31 +1,80 @@
+import sys
+from typing import Optional
 from typing import Sequence
-
-from .buf import Buffer
+from typing import Tuple
 
 
 class Window:
+    MAX_CX = sys.maxsize
+
     def __init__(
         self,
-        buf: Buffer,
-        width: int,
-        height: int,
+        lines: Optional[Sequence[str]] = None,
+        width: int = 0,
+        height: int = 0,
+        cx: int = 0,
+        cy: int = 0,
         bx: int = 0,
         by: int = 0,
     ):
-        self._buf = buf
+        self._lines = lines or []
         self.width = width
         self.height = height
+        self.cx = cx
+        self.cy = cy
         self.bx = bx
         self.by = by
 
-    @property
-    def cx(self) -> int:
-        return self.bx + self._buf.cx
+        self._cx_hint = cx
+
+    def up(self) -> "Window":
+        if self.cy > 0:
+            self.cy -= 1
+            self._set_cx_after_vertical_movement()
+        return self
+
+    def down(self) -> "Window":
+        if self.cy < len(self._lines) - 1:
+            self.cy += 1
+            self._set_cx_after_vertical_movement()
+        return self
+
+    def _set_cx_after_vertical_movement(self) -> None:
+        if self.cx > self._max_cx:
+            # Cursor exceeded the line
+            if self.cx > self._cx_hint:
+                self._cx_hint = self.cx
+            self.cx = max(self._max_cx, 0)
+        else:
+            self.cx = min(self._cx_hint, self._max_cx)
+
+    def left(self) -> "Window":
+        if self.cx > 0:
+            self.cx -= 1
+            self._cx_hint = self.cx
+        return self
+
+    def right(self) -> "Window":
+        if self.cx < self._max_cx:
+            self.cx += 1
+            self._cx_hint = self.cx
+        return self
+
+    def home(self) -> "Window":
+        self.cx = self._cx_hint = 0
+        return self
+
+    def end(self) -> "Window":
+        self._cx_hint = self.MAX_CX
+        self.cx = min(self._cx_hint, self._max_cx)
+        return self
 
     @property
-    def cy(self) -> int:
-        return self.by + self._buf.cy
+    def _max_cx(self) -> int:
+        return len(self._lines[self.cy]) - 1
 
-    @property
-    def lines(self) -> Sequence[str]:
-        return self._buf._lines[-self.by : (self.height - self.by)]
+    def screen_cursor(self) -> Tuple[int, int]:
+        return (self.bx + self.cx, self.by + self.cy)
+
+    def screen_lines(self) -> Sequence[str]:
+        return self._lines[-self.by : (self.height - self.by)]
diff --git a/tests/buf_test.py b/tests/buf_test.py
deleted file mode 100644
index 2609e6b..0000000
--- a/tests/buf_test.py
+++ /dev/null
@@ -1,130 +0,0 @@
-from editor.main import Buffer
-
-
-def test_buffer_up():
-    assert Buffer(["foo", "bar"], cy=1).up().cy == 0
-
-
-def test_buffer_up_at_first_line():
-    assert Buffer(["foo"]).up().cy == 0
-
-
-def test_buffer_up_passed_shorter_line():
-    # It correctly resets to a shorter and then longer line
-    buf = Buffer(["longer line", "short", "long line"], cx=8, cy=2)
-    buf.up()
-    assert buf.cx == 4
-    assert buf.cy == 1
-    buf.up()
-    assert buf.cx == 8
-    assert buf.cy == 0
-
-    # It correctly resets to a shorter and then medium line
-    buf = Buffer(["long line", "short", "longer line"], cx=10, cy=2)
-    buf.up()
-    assert buf.cx == 4
-    assert buf.cy == 1
-    buf.up()
-    assert buf.cx == 8
-    assert buf.cy == 0
-
-    # It correctly resets cx on empty lines
-    buf = Buffer(["", "foo"], cx=4, cy=1)
-    buf.up()
-    assert buf.cx == 0
-    assert buf.cy == 0
-
-    # It correctly resets cx on lines of the same length
-    buf = Buffer(["short", "short"], cx=4, cy=1)
-    buf.up()
-    assert buf.cx == 4
-    assert buf.cy == 0
-
-    # It correctly resets cx hint after horizontal movement
-    buf = Buffer(["foo", "", "bar"], cy=2)
-    buf.right().up().up()
-    assert buf.cx == 1
-    assert buf.cy == 0
-    buf.left().down().down()
-    assert buf.cx == 0
-    assert buf.cy == 2
-
-
-def test_buffer_down():
-    assert Buffer(["foo", "bar"]).down().cy == 1
-
-
-def test_buffer_down_passed_shorter_line():
-    # It correctly resets to a shorter and then longer line
-    buf = Buffer(["long line", "short", "longer line"], cx=8)
-    buf.down()
-    assert buf.cx == 4
-    assert buf.cy == 1
-    buf.down()
-    assert buf.cx == 8
-    assert buf.cy == 2
-
-    # It correctly resets to a shorter and then medium line
-    buf = Buffer(["longer line", "short", "long line"], cx=10)
-    buf.down()
-    assert buf.cx == 4
-    assert buf.cy == 1
-    buf.down()
-    assert buf.cx == 8
-    assert buf.cy == 2
-
-    # It correctly resets cx on empty lines
-    buf = Buffer(["foo", ""], cx=4)
-    buf.down()
-    assert buf.cx == 0
-    assert buf.cy == 1
-
-    # It correctly resets cx on lines of the same length
-    buf = Buffer(["short", "short"], cx=4)
-    buf.down()
-    assert buf.cx == 4
-    assert buf.cy == 1
-
-    # It correctly resets cx hint after horizontal movement
-    buf = Buffer(["foo", "", "bar"])
-    buf.right().down().down()
-    assert buf.cx == 1
-    assert buf.cy == 2
-    buf.left().up().up()
-    assert buf.cx == 0
-    assert buf.cy == 0
-
-
-def test_buffer_down_at_last_line():
-    assert Buffer(["foo"]).down().cy == 0
-
-
-def test_buffer_left():
-    assert Buffer(cx=1).left().cx == 0
-
-
-def test_buffer_left_at_first_char():
-    assert Buffer().left().cx == 0
-
-
-def test_buffer_right():
-    assert Buffer(["foo"]).right().cx == 1
-
-
-def test_buffer_right_at_last_char():
-    assert Buffer(["foo"], cx=2).right().cx == 2
-
-
-def test_buffer_home():
-    assert Buffer(["foo"], cx=2).home().cx == 0
-
-
-def test_buffer_end():
-    assert Buffer(["foo"]).end().cx == 2
-
-
-def test_buffer_end_makes_vertical_movement_always_move_to_last_char():
-    buf = Buffer(["short", "longer line", "long line"])
-    assert buf.end().cx == 4
-    assert buf.down().cx == 10
-    assert buf.down().cx == 8
diff --git a/tests/window_test.py b/tests/window_test.py
index 267148d..9bf0cd8 100644
--- a/tests/window_test.py
+++ b/tests/window_test.py
@@ -1,21 +1,148 @@
-from editor.buf import Buffer
 from editor.window import Window
 
 
-def test_window_cx_cy():
-    buf = Buffer(["foo", "bar", "baz"], cx=2, cy=2)
-    window = Window(buf, width=3, height=3, bx=-1, by=-1)
-    assert window.cx == 1
-    assert window.cy == 1
+def test_window_up():
+    assert Window(["foo", "bar"], cy=1).up().cy == 0
 
 
-def test_window_lines_vertical_scroll():
-    buf = Buffer(["foo", "bar", "baz"], cx=2, cy=2)
-    window = Window(buf, width=3, height=3, by=-1)
-    assert window.lines == ["bar", "baz"]
+def test_window_up_at_first_line():
+    assert Window(["foo"]).up().cy == 0
 
 
-def test_window_lines_horizontal_scroll():
-    buf = Buffer(["foo", "bar", "baz"], cx=2, cy=2)
-    window = Window(buf, width=3, height=3, bx=-1)
-    assert window.lines == ["ar", "az"]
+def test_window_up_passed_shorter_line():
+    # It correctly resets to a shorter and then longer line
+    win = Window(["longer line", "short", "long line"], cx=8, cy=2)
+    win.up()
+    assert win.cx == 4
+    assert win.cy == 1
+    win.up()
+    assert win.cx == 8
+    assert win.cy == 0
+
+    # It correctly resets to a shorter and then medium line
+    win = Window(["long line", "short", "longer line"], cx=10, cy=2)
+    win.up()
+    assert win.cx == 4
+    assert win.cy == 1
+    win.up()
+    assert win.cx == 8
+    assert win.cy == 0
+
+    # It correctly resets cx on empty lines
+    win = Window(["", "foo"], cx=4, cy=1)
+    win.up()
+    assert win.cx == 0
+    assert win.cy == 0
+
+    # It correctly resets cx on lines of the same length
+    win = Window(["short", "short"], cx=4, cy=1)
+    win.up()
+    assert win.cx == 4
+    assert win.cy == 0
+
+    # It correctly resets cx hint after horizontal movement
+    win = Window(["foo", "", "bar"], cy=2)
+    win.right().up().up()
+    assert win.cx == 1
+    assert win.cy == 0
+    win.left().down().down()
+    assert win.cx == 0
+    assert win.cy == 2
+
+
+def test_window_down():
+    assert Window(["foo", "bar"]).down().cy == 1
+
+
+def test_window_down_passed_shorter_line():
+    # It correctly resets to a shorter and then longer line
+    win = Window(["long line", "short", "longer line"], cx=8)
+    win.down()
+    assert win.cx == 4
+    assert win.cy == 1
+    win.down()
+    assert win.cx == 8
+    assert win.cy == 2
+
+    # It correctly resets to a shorter and then medium line
+    win = Window(["longer line", "short", "long line"], cx=10)
+    win.down()
+    assert win.cx == 4
+    assert win.cy == 1
+    win.down()
+    assert win.cx == 8
+    assert win.cy == 2
+
+    # It correctly resets cx on empty lines
+    win = Window(["foo", ""], cx=4)
+    win.down()
+    assert win.cx == 0
+    assert win.cy == 1
+
+    # It correctly resets cx on lines of the same length
+    win = Window(["short", "short"], cx=4)
+    win.down()
+    assert win.cx == 4
+    assert win.cy == 1
+
+    # It correctly resets cx hint after horizontal movement
+    win = Window(["foo", "", "bar"])
+    win.right().down().down()
+    assert win.cx == 1
+    assert win.cy == 2
+    win.left().up().up()
+    assert win.cx == 0
+    assert win.cy == 0
+
+
+def test_window_down_at_last_line():
+    assert Window(["foo"]).down().cy == 0
+
+
+def test_window_left():
+    assert Window(cx=1).left().cx == 0
+
+
+def test_window_left_at_first_char():
+    assert Window().left().cx == 0
+
+
+def test_window_right():
+    assert Window(["foo"]).right().cx == 1
+
+
+def test_window_right_at_last_char():
+    assert Window(["foo"], cx=2).right().cx == 2
+
+
+def test_window_home():
+    assert Window(["foo"], cx=2).home().cx == 0
+
+
+def test_window_end():
+    assert Window(["foo"]).end().cx == 2
+
+
+def test_window_end_makes_vertical_movement_always_move_to_last_char():
+    win = Window(["short", "longer line", "long line"])
+    assert win.end().cx == 4
+    assert win.down().cx == 10
+    assert win.down().cx == 8
+
+
+def test_window_screen_cursor():
+    lines = ["foo", "bar", "baz"]
+    window = Window(lines, bx=-1, by=-1, cx=2, cy=2)
+    assert window.screen_cursor() == (1, 1)
+
+
+def test_window_screen_lines_vertical_scroll():
+    lines = ["foo", "bar", "baz"]
+    window = Window(lines, width=3, height=3, by=-1, cx=2, cy=2)
+    assert window.screen_lines() == ["bar", "baz"]
+
+
+# def test_window_screen_lines_horizontal_scroll():
+#     lines = ["foo", "bar", "baz"]
+#     window = Window(lines, width=3, height=3, bx=-1, cx=2, cy=2)
+#     assert window.screen_lines() == ["oo", "ar", "az"]