455895 - Tab Preview of code samples in this page look lousy in page-previewing extensions

Status: RESOLVED WORKSFORME

(Firefox :: General, defect)

Description

[Ben Lerner]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1

As far as I understand it, the Tab Preview and Last Tab extensions take a snapshot of the background tabs, somehow, and displays those snapshots when you hover over the tabs or Ctrl+Tab through the tabs.  Somehow, though, this particular page yields noticeably wrong-looking results: the code samples are rendered in the wrong font relative to the rest of the page, which I think is a rendering bug in handling media-specific CSS.

Reproducible: Always

Steps to Reproduce:
1. Open above URL, and at least one other tab
2. Have the Tab Preview extension installed (http://ted.mielczarek.org/code/mozilla/tabpreview/)
3. Mouse over the MDC tab while it's in the background
4. Have the Last Tab extension installed (http://timothyhumphrey.name/firefox/)
5. Ctrl+Tab until MDC tab is previewed
Actual Results:  
See the attached picture for the preview I see with Tab Preview; the Last Tab results are identical.  For comparison, the right side of the picture shows the preview when CSS is disabled -- you can see that the fonts look much more reasonable.


Last Tab and the new Ctrl-Tab extension are incompatible with each other, so I can't test whether Ctrl-Tab yields the same results.  I'd bet it would...  

In Tools->Options->Fonts->Advanced, I have my monospaced font set to Courier New 13pt, nothing exotic there, so I doubt it's a missing-font kind of problem.

Finally, I haven't checked this yet in a nightly Firefox; maybe some of the CSS fixes going into Fx3.1 will fix this?

Comment 1

[Ben Lerner]

Attachment: Screenshot showing bad preview of tab, and preview of tab without CSS

Comment 2

[Tyler Downer [He/Him]]

This is a problem with an extension. please contact the developer of the extension, as those bugs don't belong on b.m.o.

Comment 3

[Ben Lerner]

No, actually, I don't think it's a problem with the extension.  That's why I bothered filing it here -- when I saw two extensions result in the same behavior, and that behavior appears to be a CSS rendering bug, I thought it appropriate to file here.

Comment 4

[Tyler Downer [He/Him]]

If this issue s showing up in the extension, it is an extension issue. The issue looks like there is simply not very much room in the preview window, so it is compressing the preview.

--> INVALID (Extension, not issue with Firefox)

You can try in Safe Mode (though that will disable all extensions).

Comment 5

[Ben Lerner]

Again, no, sorry if I'm being unclear -- comparing the two preview images, you can see that the right-side image shows the same text as the left-side image, but the fixed-width text is in proportion to the other text of the page, unlike the left-side image where the fixed-width text is of much larger font size but still-small line height, resulting in the garbled image.  

To prove it's not just an extension issue, try viewing the same URL in Firefox, and repeatedly shrinking the page with Ctrl-minus, to its minimum setting.  You can see the fixed-width text start getting garbled at lowest settings, though not quite as garbled as the extensions (which use even smaller font sizes, I guess).

Comment 6

[Tyler Downer [He/Him]]

If this is happening in Safe Mode with Ctrl+-, then it is a bug in Firefox. so far, this has been with the extension, which is not a bug in Firefox. You can submit it under a new bug report, one bug per report please.

Comment 7

[Ben Lerner]

It does indeed happen in Safe Mode with Ctrl+-, with exactly the same visual results: the fixed-width font shrinks to a minimum size that is *larger* than the minimum size of the surrounding text, while its line spacing continues shrinking, resulting in garbled output similar to that seen in the screenshot.  The extensions I mentioned help show the broken behavior, as an even more extreme case that the minimum Ctrl+- setting.  Since you're more an expert of b.m.o than I am (I just try to help when I can), feel free to re-file it wherever you think it is most appropriate for Firefox.

Comment 8

[Tyler Downer [He/Him]]

Can you give an example site that this happens on?

Comment 9

[Tyler Downer [He/Him]]

Never mind, I see this issue.

Comment 10

[Tyler Downer [He/Him]]

This is a mass search for bugs which are in the Firefox General component, are
UNCO, have not been changed for 500 days and have an unspecified version. 

Reporter, can you please update to Firefox 3.6.10 or later, create a fresh profile, http://support.mozilla.com/en-US/kb/managing+profiles, and test again. If you still see the issue, please update this bug. If the issue is gone, please set the status to RESOLVED > WORKSFORME.

Comment 11

[Ben Lerner]

This is still an issue in Firefox 3.6.10 with a fresh profile, regular mode, and safe mode.  I don't know how thoroughly font handling has been overhauled in Fx4, and I don't have a machine convenient to test that on right now, so I don't know if it's a problem there.  I'm just curious, apropos comment 9, where you agreed you saw this issue too, why this is still unconfirmed?

Comment 12

[Tyler Downer [He/Him]]

This probably slipped through the cracks. I'll retest later and see if this is still a problem with Firefox 4.

Comment 13

[Ben Lerner]

No worries; I'm glad someone's triaging old bugs! :)

Comment 14

[Tyler Downer [He/Him]]

Ben, I've tested with Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b8pre) Gecko/20101009 Firefox/4.0b8pre, and I'm not seeing this problem anymore. Would you mind downloading a Firefox trunk build and retesting there?
ftp://ftp.mozilla.org/pub/firefox/nightly/latest-mozilla-central/
Some pretty major changes have occurred in Firefox 4, so it might be the problem is gone now.

Comment 15

[Ben Lerner]

Attachment: Badly sized monospaced fonts on Fx4.0b8

Hmm, I just installed firefox-4.0b8pre.en-US.win64-x86_64.installer.exe from the link above, and as soon as it opened (firefox has never been installed on this machine before, so new profile, new everything) it crashed with an access violation trying to read location (uint)-1...

In safe mode, Firefox will launch cleanly.  Then I go to the selenic.com link above, scroll down until the monospaced font is visible, and I trigger Panorama.  Since it gives thumbnail-sized previews of the pages, this seems a good analogue for the Tab Preview extension (which doesn't yet work on Fx4).  The results are attached: the monospaced fonts get down to a minimum size but no further, but the line-spacing gets very tiny and so we still get the bad results from before.

Comment 16

[Tim (fmdeveloper)]

Reporter -> Are you still experiencing this issue with the latest version of Firefox 5? Does the issue occur with the latest nightly? http://nightly.mozilla.org/

Comment 17

[Ben Lerner]

Using Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0) Gecko/20100101 Firefox/5.0, I no longer see the buggy results I saw before.  Monospaced text now seems to scale in proportion to the rest of the page.  I don't have a machine handy to test Aurora or nightly builds, but hopefully it hasn't regressed :)

Thanks.

Comment 18

[Tim (fmdeveloper)]

Closing per comment 17