Customize: custom CSS textarea is scrolled to top when pressing tab

[celloexpressions]

When there's enough CSS for a scrollbar on the textarea, it jumps to the top whenever you press the tab key. This is a very frustrating experience as a user; milestoning for 4.7.1 for investigation since it's introduced by a new 4.7 feature. See forthcoming screencast.

[tyxla]

Remove textarea scrolltop alteration on keydown

[tyxla]

It appears that on tab keydown the scrolltop of the textarea was being altered. I'm not seeing any need for this to be done - in any case, after inserting the tab in the textarea content (with or without enough content to allow scrolling), the browser will not move the scrolled position.

I've attached a diff to remove the alterations that we're doing on the textarea's scrolltop.

[celloexpressions]

It looks like that code was trying specifically to prevent this bug. It's not working correctly, and odd that it works without it. I wonder if this is happening differently in different browsers?

[westonruter]

Agreed. We need to run this through the various browsers.

See #38667 where this was introduced.

The patch was first developed by @coffee2code in ​https://meta.trac.wordpress.org/changeset/3316

[sstoqnov]

Tested and it works on all major browsers ( Chrome, Safari, Opera and Firefox ).

[westonruter]

@sstoqnov and what about IE9 and above?

[sstoqnov]

@westonruter just tested and It works on IE7+ and above.

[westonruter]

@sstoqnov oh, you tested in IE7? I'm surprised you were able to get the customizer to even load since the customizer is only supported in IE9+ now.

@celloexpressions this also works in IE on your system?

[sstoqnov]

@westonruter I am using Mac and tested in Browserstack. Not sure if I am wrong or their software doesn't work at all.
Maybe will be better if someone that uses Windows can test this again.

[tyxla]

I've just tested on Windows 10 and I verify that it works as expected on IE9 and above.

[celloexpressions]

Confirmed that 39134.diff​ works in Edge, IE11, and IE11 emulating IE9. Let's commit.

[westonruter]

In 39557:

Customize: Prevent scrolling custom_css textarea to top when pressing tab.

Props tyxla, sstoqnov for testing, celloexpressions for testing.
See #38667.
Fixes #39134.

[westonruter]

Re-opening for 4.7.1

[dd32]

In 39569:

Customize: Prevent scrolling custom_css textarea to top when pressing tab.

Props tyxla, sstoqnov for testing, celloexpressions for testing.
See #38667.
Merges [39557] to the 4.7 branch.
Fixes #39134.