The calibre editbook file preview window doesn't show the text properly.

release details:
Description: Ubuntu Cosmic Cuttlefish (development branch)
Release: 18.10

~$ apt-cache policy calibre
calibre:
  Installed: 3.31.0+dfsg-1
  Candidate: 3.31.0+dfsg-1
  Version table:
 *** 3.31.0+dfsg-1 500
        500 http://127.0.0.1:3142/mirror.yandex.ru/ubuntu cosmic/universe amd64 Packages
                100 /var/lib/dpkg/status

The file preview window should show the file text properly to fit the preview window, but it only shows a portion of the file text.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: calibre 3.31.0+dfsg-1
ProcVersionSignature: Ubuntu 4.18.0-7.8-generic 4.18.5
Uname: Linux 4.18.0-7-generic x86_64
ApportVersion: 2.20.10-0ubuntu11
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Oct 6 18:09:56 2018
InstallationDate: Installed on 2018-09-29 (7 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Beta amd64 (20180927)
PackageArchitecture: all
SourcePackage: calibre
UpgradeStatus: No upgrade log present (probably fresh install)