Thunderbird Conversations & font issues

Jonathan Protzenko jonathan.protzenko at
Thu May 12 09:52:40 UTC 2011

Hi all,

I've pushed a new build of Thunderbird Conversations
that contains a fix for the font issue (discussed on
tb-planning). Here's the set of constraints that I have to deal with:
- the default size for proportional is 16px (17px on Mac) and the
default size for monospaced is 12px (13px on Mac),
- the conversation UI is designed with a font size of 12px in mind,
- if the user has selected bigger fonts, we want the conversation UI to
be proportionally bigger,
- we don't want to tweak the default font size, as this would break
other stuff in thunderbird (welcome to shredder start page, content tabs
such as google calendar, etc. would all be smaller and most likely

The solution I picked is:
- make the conversation chrome font size 75% of the default font (we
previously had 12px hardcoded everywhere, so this is an improvement),
- make the proportional font size for message bodies 75% of the
proportional font size,
- leave the font size for monospaced message bodies untouched.

This means for people who left their defaults untouched (which I assume
is the majority of the audience) 12px everywhere, which happens to match
what Andy Chung had in mind when he made the initial mockup. This gives
the best, most consistent look for the Thunderbird Conversations UI.

- For people who bumped on purpose their font size (say, 20px for
proportional and 15px for monospace), the conversation ui and
proportional message bodies will be *consistent and larger*. In
practice, this gives 15px both for the conversation chrome and the
message bodies. This is consistent, and the conversation chrome now
scales up too (it previously didn't, because we had 12px hardcoded).
- For people who shrinked their font sizes, they'll probably have to
undo this, since I believe anything below 12px is incredibly hard to read.

Font topics are controversial, and I do hope this is an acceptable
compromise. However, if anyone has an ultimate solution that I failed to
see, please let me know !


PS : the Thunderbird default font size is accessible from the
preferences, in the "display" section.
PPS : I also made the tooltips, the menus, and the dropdowns
proportionally bigger, so that the same amount of text still fits.

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