572649 - Attempting to scroll a textarea with a horizontal scrollbar using the mouse jumps to its bottom right (focusing a textarea with the mouse scrolls the selection into view)

Status: VERIFIED FIXED

(Core :: Layout: Form Controls, defect)

Description

[John P Baker]

Attachment: testcase

This has hit me a few times over the last couple of days when viewing text in a textarea.

1) Load attachment
2 [review]) Click on scrollbar to move down (or right)

Textarea becomes positioned at last character.

Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9.3a6pre) Gecko/20100616 Minefield/3.7a6pre

Comment 1

[John P Baker]

Similarly context-clicking in the unfocussed textarea.

Comment 2

[John P Baker]

ehsan, you seem to have done a few changes in this area recently.

Comment 3

[(no longer active)]

This happens because the textarea is focused when you click a scroll button, which causes us to scroll its selection into view, which causes this behavior (see bug 353539 where this behavior was added).

I guess we could detect that we're getting the focus because of a click on the scrollbar, but I'm not sure how to do that.

Comment 4

[Robert O'Callahan (:roc) (email my personal email if necessary)]

I think we can distinguish click-to-focus from other kinds of focus. We shouldn't scroll into view when clicking to focus.

Comment 5

[John P Baker]

(In reply to comment #4)
> I think we can distinguish click-to-focus from other kinds of focus. We
> shouldn't scroll into view when clicking to focus.

It may not only be click-to-focus
1) Load attachment.
2) Press tab key.

Comment 6

[(no longer active)]

Neil, could you please answer comment 4?

Comment 7

[Neil Deakin]

You can detect what method was last used to focus with nsIFocusManager::GetLastFocusMethod 

But why do you want to special case this considering comment 5? Shouldn't the textarea already be scrolled to the caret to start with?

Comment 8

[(no longer active)]

Hmm, I guess one solution would be to initialize the selection to the beginning of the textarea initially instead of its end, but I'm not sure if we want that.  That's what Webkit does BTW.

Comment 9

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

In general, though, caret position can be outside of the visible area due to mousewheel scrolling.

Comment 10

[(no longer active)]

(In reply to comment #9)
> In general, though, caret position can be outside of the visible area due to
> mousewheel scrolling.

Hmm, yes.  So, in that case, I'm not really sure how to address this problem.

Comment 11

[Robert O'Callahan (:roc) (email my personal email if necessary)]

We can make clicking in the scrollbar focus the textarea without scrolling anything into view.

Ehsan, do you want this?

Comment 12

[(no longer active)]

(In reply to comment #11)
> We can make clicking in the scrollbar focus the textarea without scrolling
> anything into view.

What about comment 5?

> Ehsan, do you want this?

Sure.

Comment 13

[Robert O'Callahan (:roc) (email my personal email if necessary)]

It's not clear to me that scrolling the caret into view when we tab into the control is wrong, whereas it seems to clear to me that this bug as filed (comment #0) is a real bug.

Comment 14

[(no longer active)]

Attachment: Patch (v1)

Comment 15

[(no longer active)]

http://hg.mozilla.org/mozilla-central/rev/3ea256acb017

Comment 16

[John P Baker]

Verified. [That makes my CMS usable again.]

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