[TYPO3-core] RFC: Bug #7817: Transparent PNGs do not work in IE 6

[Dmitry Dulepov [typo3]]

Hi!

Ingo Renner wrote:
> Problem:
> IE6 is too stupid to handle alpha channel PNGs (and basically everything 
> else that's fun)
> 
> Solution:
> use Javascript to apply Microsoft's special filter where this works. 
> However, there are places where this didn't work (background images like 
> the arrows in the module menu with t3skin). After trying to make this 
> work for two days now (together with Steffen) I give up... I've added 
> the affected images in a new folder /typo3/gfx/ie6/ so that we know that 
> we can safely remove them at some point. These images are used through 
> an additional stylesheet for IE6 in t3skin.

This will not work as expected in all cases:

+			if(/MSIE 6/.test(navigator.userAgent)) {

I have seen several absolutely normal installation of MSIE 7, which have the following user agent:

Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) )

This is not a error. Look here: http://www.zytrax.com/tech/web/msie-history.html

Your patch will be triggered for all such MSIE7s too, which is not necessary. You need to check that there is no "MSIE 7" in the string. Also Opera may simulate MSIE6. If you want to skip Opera, check for "compatible; MSIE 6", not just for "MSIE 6".  And finally, why regexp and not indexOf?

-- 
Dmitry Dulepov
TYPO3 core team
Web: http://typo3bloke.net/
Skype: callto:liels_bugs
"Nothing is impossible. There are only limits to our knowledge"