1028503 - Font size for plain text display

Status: NEW

(Thunderbird :: Message Reader UI, defect)

Description

[Heinrich Schuchardt]

Attachment: icedove.png

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:29.0) Gecko/20100101 Firefox/29.0 Iceweasel/29.0.1 (Beta/Release)
Build ID: 20140524000300

Steps to reproduce:

I am using a 160 dpi 3860x2160 monitor and Debian Jessie with Kernel 3.15.0 x86_64.
The dpi setting of the X11 system is 160 dpi (set by xrandr).
In preferences display I chose
Monospace: monospace 24
For message display I chose
Message Body: As Plain Text


Actual results:

The message body is displayed as 12px making it illegible.


Expected results:

Plain text display should use the monospace font given in the preferences.

The displayed font size should reflect the dpi setting of the system. Hence it should not be necessary to set a larger font.

Comment 1

[Heinrich Schuchardt]

This is the source of the mail shown in appendix icedove.png:

Subject: official DRM Kernel
Content-Type: text/html; charset=UTF-8
Date: Sat, 21 Jun 2014 06:03:12 +0200

<a href="http://cgit.freedesktop.org/~airlied/linux">http://cgit.freedesktop.org/~airlied/linux</a>/<br>
<br>
Best regards<br>
<br>
Heinrich Schuchardt<br>
<br>
<a href="http://www.xypron.de">http://www.xypron.de</a>

Comment 3

[Mark Banner (:standard8)]

I can confirm this issue with Thunderbird 78.x.

For plain text emails, there is no apparent way for the user to change the size of the text if "Use fixed width font for plain text messages" is selected.

Digging into the code, the size is being injected as a style by libmime here: https://searchfox.org/comm-central/rev/a10c693ce0a1f895441258834137368359bcc6be/mailnews/mime/src/mimetpla.cpp#131-149

Looking at GetMailNewsFont, it seems to use the font.size.monospace.* preferences.

In my case, it is using the font.size.monospace.x-unicode preference. This is interesting, because the "Fonts & Encodings" UI is setting the font.size.monospace.x-western preference.

Hence, the user can't affect the size of the plain text messages from the UI.

Comment 4

[Mark Banner (:standard8)]

The code also does not respect the "minimum font size" option.

Comment 5

[Stans]

The issue is present in Thunderbird 91 (91.1.1) as well and while I offer a workaround using css here https://support.mozilla.org/questions/1350263, it would be nice if the preferences took effect for display of plain text messages using a monospace font.

Comment 6

[jburrell]

I believe the bug is in...
Content-Type: text/plain; charset="iso-8859-1"
vs.
Content-Type: text/plain; charset="UTF-8"

The former seems to respect the accessible user font settings for mono-spaced fonts. The latter can only be changed by going into Config Editor, searching for font.size.monospace.x-unicode and making the change there.

Thanks to Mark Banner for the work around.