469847 - images in generated content (used for :hover, etc.) are not downloaded until they are needed, causing flickering

Status: NEW

(Core :: CSS Parsing and Computation, defect)

Description

[Wolfgang Uhr]

Attachment: This file is a reduced testcase to demonstrate different different problems described above.

Hello

I've attached a small html-file to demonstrate the Problem. This file contains a HTML-Part and a CSS part and the css requires some pictures on http://devsup.de/. You may download thoose pictures for internal use but to demonstrate the problem, this construction is the better one.

First I've demonstrated a picture and a short text into the css-pseudo-classes:

a:link:before
a:visited:before
a:link:focus:before
a:visited:focus:before
a:link:hover:before
a:visited:hover:before
a:link:hover:focus:before
a:visited:hover:focus:before
a:link:active:before
a:visited:active:before

First Problem:

You have visited no linked page in the list inserted into the html-code of the attachment file and the setting of a:link:before will be show in all cases. If you activate one of the cases "hover" or "focus" for that link. The acual Icon will be unshown - cleared from screnn - and the new actual icon will be shon. In Oder to do this, the browser downloads the new picture by its own http-request. This Request may take some seconds and during this time, no picure is shown. 

If you visit a page and go back by the browser, it works correct. One Link shows the picture of a:visited:before and the others a:link:before. This is correct.

Second Problem:

Then you can step throug this link collection using the tab key and you'll find a further time delay, if the included picture is new for the browser. 

Third Problem:

If you are hovering the elemenets - the next time-delay effects will occur.

Last Problem

You hover a link and press down the mouse button - kepp them pressed down - and move them outside the hover-area of the link. There you can set free the mouse button. If the mouse is down, the Icon of a:link:hover:before or a:visited:hover:before is shown. But normally the active states should be shown. But this ist done if the mouse button has been released outside of the hover region of the link. 
Furthermore if the link is in the state "active", it will stay in this mode until an other link is activated in the same way. 

I hope that this helps to solve the problem. 

Best regards 
Wolfgang Uhr

Comment 1

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

The first three problems all seem to be the same:  that we don't download images in generated content until they are used.

Your last problem seems to be two separate problems:

First:
> If the mouse is down, the Icon of a:link:hover:before or
> a:visited:hover:before is shown. But normally the active states should be
> shown.

It's actually the :hover:focus state that is shown, and this is correct, since when a link matches :hover, :focus, and :active (which it does in this case), the :hover:focus rule wins because of CSS selector specificity.  So I think this bug is invalid.

Second:
> Furthermore if the link is in the state "active", it will stay in this mode
> until an other link is activated in the same way. 

This is a duplicate of bug 379272.

Comment 2

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

I'm resummarizing this bug to be about the first three issues, which are really all the same, since I think the last issue (both parts) are not relevant (see previous comment).

But in the future, please don't put multiple issues in a single bug report.  (That said, your First...Third issues are pretty clearly all the same.)

Comment 3

[Wolfgang Uhr]

> But in the future, please don't put multiple issues in a single bug report. 
(That said, your First...Third issues are pretty clearly all the same.)

Ok, sorry for doing it ...