305635 - Customizing "Display Resolution" reveals incorrect behaviour.

Status: RESOLVED INCOMPLETE

(Core Graveyard :: GFX, defect)

Description

[Mike Hoye]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.10) Gecko/20050725 Firefox/1.0.6 (Ubuntu package 1.0.6)
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.10) Gecko/20050725 Firefox/1.0.6 (Ubuntu package 1.0.6)

Using extremely large or small values for the "Display Resolution" option
reveals that it is being handled backwards. Setting it to a very low value like
10 and restarting FF should display your page in a very small font, since bigger
pixels means fewer pixels per inch. Likewise, very high DPI settings (800 dpi)
should result in extremely large fonts. 

The opposite is true, in both cases - setting the Display Resolution option to
15 dpi results in huge fonts, and setting it to 800 DPI results in tiny fonts.

You also need to set these things manually before running Firefox, because very
large or very small values for Display Resolution breaks the dialogs in a number
of places. 


Reproducible: Always

Steps to Reproduce:
1. With FF closed;  in prefs.js, set
user_pref("browser.display.screen_resolution"...) to 10, or 800.
2. Open, look at Google for display breakage and edit->prefs for dialog breakage.
3. Close, set user_pref to the other value, try again. 

Actual Results:  
As described, the fonts are sized incorrectly for extreme display resolution values

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Looks like this was originally filed as bug 305623 and marked invalid by the
reporter.

Comment 2

[Felix Miata]

Attachment: screenshot - 800 DPI Seamonkey/20 DPI Firefox

I can't see any point in the extreme settings suggested by the reporter, but
given that the UI ignores the browser.display.screen_resolution setting, this
is actually WFM at 1792x1344 resolution with system DPI 144. In user.js I set
browser.display.screen_resolution for Seamonkey to 800 and for Firefox to 20.

As to the reported 720 DPI by
http://members.ij.net/mrmazda/auth/dpi-screen-window.html in Seamonkey,
http://members.ij.net/mrmazda/tmp/dpi-broken.html tables what I think is some
JS rounding bug in Gecko I've yet to find filed.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

This could easily be a bug in a patch that Ubuntu ships.  Have you tested that
the bug occurs in the builds on http://www.mozilla.org/ ?

Comment 4

[Tony Mechelynck [:tonymec]]

No reply in 2½ years => INCOMPLETE.
Also, Firefox 1.0.x is obsolete now. If you want to REOPEN, please say in which current version of Firefox or SeaMonkey, downloaded directly from the Mozilla site, you see this bug.