From 01e00bac9dffab8dbc0bbd5d580c61e13022b9a7 Mon Sep 17 00:00:00 2001
From: thankyouverycool <66646555+thankyouverycool@users.noreply.github.com>
Date: Tue, 16 Feb 2021 08:58:01 -0500
Subject: [PATCH] LibGUI: Set correct ranges for hidable scrollbars

Fixes vertical and horizontal overscroll in widgets that allow
unnecessary scrollbars to be hidden.
---
 .../Libraries/LibGUI/ScrollableWidget.cpp     | 25 ++++++++++++-------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/Userland/Libraries/LibGUI/ScrollableWidget.cpp b/Userland/Libraries/LibGUI/ScrollableWidget.cpp
index 9e724a6c40..ea04ada81f 100644
--- a/Userland/Libraries/LibGUI/ScrollableWidget.cpp
+++ b/Userland/Libraries/LibGUI/ScrollableWidget.cpp
@@ -111,19 +111,26 @@ void ScrollableWidget::update_scrollbar_ranges()
     auto available_size = this->available_size();
 
     int excess_height = max(0, m_content_size.height() - available_size.height());
-    m_vertical_scrollbar->set_range(0, excess_height);
-    m_vertical_scrollbar->set_page_step(available_size.height());
-
-    if (should_hide_unnecessary_scrollbars())
-        m_vertical_scrollbar->set_visible(excess_height > 0);
-
     int excess_width = max(0, m_content_size.width() - available_size.width());
-    m_horizontal_scrollbar->set_range(0, excess_width);
-    m_horizontal_scrollbar->set_page_step(available_size.width());
 
-    if (should_hide_unnecessary_scrollbars())
+    auto vertical_initial_visibility = m_vertical_scrollbar->is_visible();
+    auto horizontal_initial_visibility = m_horizontal_scrollbar->is_visible();
+
+    if (should_hide_unnecessary_scrollbars()) {
+        m_vertical_scrollbar->set_visible(excess_height > 0);
         m_horizontal_scrollbar->set_visible(excess_width > 0);
+    }
 
+    if (m_vertical_scrollbar->is_visible() != vertical_initial_visibility || m_horizontal_scrollbar->is_visible() != horizontal_initial_visibility) {
+        available_size = this->available_size();
+        excess_height = max(0, m_content_size.height() - available_size.height());
+        excess_width = max(0, m_content_size.width() - available_size.width());
+    }
+
+    m_horizontal_scrollbar->set_range(0, excess_width);
+    m_horizontal_scrollbar->set_page_step(visible_content_rect().width() - m_horizontal_scrollbar->step());
+
+    m_vertical_scrollbar->set_range(0, excess_height);
     m_vertical_scrollbar->set_page_step(visible_content_rect().height() - m_vertical_scrollbar->step());
 }