TYPO3 Core

... taken from the thread mentioned in additional info:
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After some debugging I found out that somehow that black instead of transparent background gets generated by PHP/GD's own function ImagePng() when called in t3lib_iconWorks::imagecopyresized().

This function get's called the first time to apply the user icon to the extension icon. The second time that function get's called to apply the little clock icon. When it get's called that second time imagepng() turns that transparent background into a black one.

There's a longer comment above t3lib_iconWorks::imagecopyresized() where Kasper tries to explain why it uses the way through IM instead of PHP/GD's native imagecopyresized().
However when forcing TYPO3 to use the native php function all works well. That's why I'd propose to always use PHP's native imagecopyresized() as in the patch.

This is a follow up on the RFC "Bugfix for Image Generation in t3lib_div" from Benni Mack in core list at 13.09.2007

The szenario to test all this should be:

• PHP 5.1+ or 5.2+
• IM or GM
• GD2 (should be built into PHP)
• [GFX][gdlib_png] = 1 (also try 0)
• generation of a individual record icon with at least two overlay icons (user, time, access restricted page section, ...)
  (issue imported from #M6692)