1014807 - Newlines at the end of a textarea do not increase its scrollable area, if there's a character typed at the bottom of the textarea

Status: RESOLVED DUPLICATE of bug 439462

(Core :: Layout, defect)

Description

[Daniel Holbert [:dholbert]]

STR:
 0. View attached testcase. Then follow steps in testcase (copypasted here):
 1. Click in the text area.
 2. Hit/hold "Enter" key until a scrollbar appears.
 3. Type a character
 4. Hit/hold "Enter" some more.
 5. Try to scroll to the bottom of all the newlines you just added. Did they add any scrollable space?

ACTUAL RESULTS: The newlines added in step 4 do not have any visual effect -- they don't affect the scrollbar, and they don't add any scrollable space, according to how PageUp/PageDown/uparrow/downarrow. (The cursor does disappear navigating through the newlines when I hit downarrow, but the scroll position / scrollbar don't change -- they indicate that I'm already at the end of the scrollable area.)

I think this is a recent regression. I noticed this when completing the "Description" field for a bug at Bugzilla.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

Comment 2

[Daniel Holbert [:dholbert]]

Yup, this is a regression in today's nightly.

Yesterday's nightly is good:
http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/05/2014-05-21-03-02-00-mozilla-central/firefox-32.0a1.en-US.linux-x86_64.tar.bz2
Built from https://hg.mozilla.org/mozilla-central/rev/9d8d16695f6a

Today's nightly is bad:
http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/2014/05/2014-05-22-03-02-04-mozilla-central/firefox-32.0a1.en-US.linux-x86_64.tar.bz2
Built from https://hg.mozilla.org/mozilla-central/rev/b40296602083

Regression pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=9d8d16695f6a&tochange=b40296602083

Comment 3

[Daniel Holbert [:dholbert]]

Mozregression gives me this tight regression window:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=96f69a915843&tochange=c3f1ab75ea51

So, this is a regression from https://hg.mozilla.org/integration/mozilla-inbound/rev/c3f1ab75ea51 for Bug 421436.

Comment 4

[Daniel Holbert [:dholbert]]

smontagu, do you have cycles to look into this in the next day or two?

(I wonder if perhaps we should back out bug 421436 until we have a fix for this? This bug is easy to hit & fairly annoying when typing in text areas, e.g. in bugzilla bug-description/comment fields & in Zimbra's email-composing view, and probably in heaps of other places.)

Comment 5

[Simon Montagu :smontagu]

Yes, dammit, I probably won't be able to look at this before Sunday so we should probably back out bug 421436 for now.

FWIW, this sounds similar to bug 439462, which was a regression from the first reincarnation of bug 421436.

Comment 6

[Daniel Holbert [:dholbert]]

Yup. Looks like a dupe, but the STR over there just weren't quite specific enough. Duping.

(I only hit this bug when there's text that's been entered after the first "page" of the textbox - not if the textbox remains empty, and not if the only text I've entered is above the region where scrolling becomes necessary.)