From 2ad7fdc33ffb360d3ee0684821fd2362de9eb04f Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 10 Mar 2021 22:54:10 +0530
Subject: [PATCH] E-book viewer: In paged mode, fix scrolling not working
 correctly when margins are set to zero. Fixes #1918105 [back keyboard
 shortcut not working
 [solved]](https://bugs.launchpad.net/calibre/+bug/1918105)

---
 src/pyj/read_book/paged_mode.pyj | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/pyj/read_book/paged_mode.pyj b/src/pyj/read_book/paged_mode.pyj
index 9d87088bbb..4cd35d220a 100644
--- a/src/pyj/read_book/paged_mode.pyj
+++ b/src/pyj/read_book/paged_mode.pyj
@@ -282,6 +282,8 @@ def layout(is_single_page, on_resize):
     # the window inline dimension, with their separator margins
     wi = col_size = screen_inline = scroll_viewport.inline_size()
     margin_size = (opts.margin_left + opts.margin_right) if scroll_viewport.horizontal_writing_mode else (opts.margin_top + opts.margin_bottom)
+    # a zero margin causes scrolling issues, see https://bugs.launchpad.net/calibre/+bug/1918437
+    margin_size = max(1, margin_size)
     gap = margin_size
     if n > 1:
         # Adjust the margin so that the window inline dimension satisfies