From 420b2f65b40c84106c39549823141385b16730f3 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Mon, 14 Oct 2019 17:26:51 +0530
Subject: [PATCH] Edit book: Fix a crash when editing CSS files caused by a
 behavior change in Qt 5.13. Fixes #1846760 [ebook editor crashes out when
 scrolling](https://bugs.launchpad.net/calibre/+bug/1846760)

Apparently, if a QTextFormat.FormatRange object is garbage collected by
python it is no longer safe to use a previously stored reference to it
QTextFormat object
---
 src/calibre/gui2/tweak_book/editor/text.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/calibre/gui2/tweak_book/editor/text.py b/src/calibre/gui2/tweak_book/editor/text.py
index 86c8739399..aceaf6d154 100644
--- a/src/calibre/gui2/tweak_book/editor/text.py
+++ b/src/calibre/gui2/tweak_book/editor/text.py
@@ -741,12 +741,10 @@ class TextEdit(PlainTextEdit):
             if r.start <= pos <= r.start + r.length and r.format.property(SYNTAX_PROPERTY):
                 return r
 
-    def syntax_format_for_cursor(self, cursor):
-        return getattr(self.syntax_range_for_cursor(cursor), 'format', None)
-
     def show_tooltip(self, ev):
         c = self.cursorForPosition(ev.pos())
-        fmt = self.syntax_format_for_cursor(c)
+        fmt_range = self.syntax_range_for_cursor(c)
+        fmt = getattr(fmt_range, 'format', None)
         if fmt is not None:
             tt = unicode_type(fmt.toolTip())
             if tt: