From 1e4dd1cee482309589dc47a7b2b448d24811c3e2 Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Thu, 23 Mar 2023 20:59:44 +0000
Subject: [PATCH] fix scrollbar thumb height

---
 src/textual/scrollbar.py               | 4 ----
 src/textual/widget.py                  | 1 +
 tests/snapshot_tests/test_snapshots.py | 6 ++++++
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/textual/scrollbar.py b/src/textual/scrollbar.py
index df5516ce9..f3dbc76cb 100644
--- a/src/textual/scrollbar.py
+++ b/src/textual/scrollbar.py
@@ -112,10 +112,6 @@ class ScrollBarRender:
 
             thumb_size = window_size / step_size * len_bars
 
-            if thumb_size < len_bars:
-                virtual_size += step_size
-                step_size = virtual_size / size
-
             start = int(position / step_size * len_bars)
             end = start + max(len_bars, ceil(thumb_size))
 
diff --git a/src/textual/widget.py b/src/textual/widget.py
index 9bf9966c0..8d6e62a21 100644
--- a/src/textual/widget.py
+++ b/src/textual/widget.py
@@ -2664,6 +2664,7 @@ class Widget(DOMNode):
         self._check_refresh()
 
     def _check_refresh(self) -> None:
+        """Check if a refresh was requested."""
         if self._parent is not None and not self._closing:
             try:
                 screen = self.screen
diff --git a/tests/snapshot_tests/test_snapshots.py b/tests/snapshot_tests/test_snapshots.py
index 75e5e7bfb..7c68f1405 100644
--- a/tests/snapshot_tests/test_snapshots.py
+++ b/tests/snapshot_tests/test_snapshots.py
@@ -334,3 +334,9 @@ def test_tabs_invalidate(snap_compare):
         SNAPSHOT_APPS_DIR / "tabs_invalidate.py",
         press=["tab", "right"],
     )
+
+
+def test_scrollbar_thumb_height(snap_compare):
+    assert snap_compare(
+        SNAPSHOT_APPS_DIR / "scrollbar_thumb_height.py",
+    )