diff -ur roundcubemail-1.4-beta136.orig/config/defaults.inc.php roundcubemail-1.4-beta136/config/defaults.inc.php

--- roundcubemail-1.4-beta136.orig/config/defaults.inc.php  2018-11-22 13:44:49.000000000 +0100

+++ roundcubemail-1.4-beta136/config/defaults.inc.php   2018-11-22 13:55:51.873258023 +0100

@@ -656,7 +656,7 @@

 //    RewriteRule ^/roundcubemail/[a-zA-Z0-9]{16}/(.*) /roundcubemail/$1 [PT]

 //    Alias /roundcubemail /var/www/roundcubemail/

 // Note: Use assets_path to not prevent the browser from caching assets

-$config['use_secure_urls'] = false;

+$config['use_secure_urls'] = true;

 // Allows to define separate server/path for image/js/css files

 // Warning: If the domain is different cross-domain access to some

@@ -665,11 +665,11 @@

 //    <FilesMatch ".(eot|ttf|woff)">

 //    Header set Access-Control-Allow-Origin "*"

 //    </FilesMatch>

-$config['assets_path'] = '';

+$config['assets_path'] = '/roundcubemail/assets/';

 // While assets_path is for the browser, assets_dir informs

 // PHP code about the location of asset files in filesystem

-$config['assets_dir'] = '';

+$config['assets_dir'] = '/usr/share/roundcubemail/public_html/assets/';

 // ----------------------------------

@@ -763,7 +763,7 @@

 // Since Google shut down their public spell checking service, the default settings

 // connect to http://spell.roundcube.net which is a hosted service provided by Roundcube.

 // You can connect to any other googie-compliant service by setting 'spellcheck_uri' accordingly.

-$config['spellcheck_engine'] = 'googie';

+$config['spellcheck_engine'] = 'pspell';

 // For locally installed Nox Spell Server or After the Deadline services,

 // please specify the URI to call it.

@@ -1164,7 +1164,7 @@

 $config['display_next'] = true;

 // Default messages listing mode. One of 'threads' or 'list'.

-$config['default_list_mode'] = 'list';

+$config['default_list_mode'] = 'threads';

 // 0 - Do not expand threads

 // 1 - Expand all threads automatically

Only in roundcubemail-1.4-beta136/config: defaults.inc.php.orig

​