[TYPO3-core] FYI: #13319: Implement plupload

[Benjamin Mack]

Hey,

some insights on the flash uploader back then:

The only reasons for the ExtJS popup window with the flash uploader were:

 * The uploading process needs to be run in the backend.php "main frame"
and not in a module (which is not necessary with HTML5), otherwise your
browser could crash if you switch to another module while uploading
(Flash sucks!)
 * The "upload now" button is needed because the flash "multiple select
files" needs to be triggered by a click.
 * Callbacks from and to modules should be possible and overridable
 * Individual filesize limits, number of files limits, override options
need to be settable.

Seems like we should think about how to integrate this in a way that
it's not just in the core for a certain version but can be used
everywhere and consistently (and as easy as possible everywhere) without
the technical clutter, without too many buttons, without unnecessary
windows.

Btw: Flash Upload with all its magic cost me 2-3 weeks to implement
because of all the problems and workarounds I had to do with frames,
flash versions and fallbacks - and because of so many UI changes so it
could be clean and simple (I'm still not satisfied with it in its
current state).

And yes: The worst mistake of mine with this Flash uploader feature was
that I didn't implement it in TCEforms right away.

All the best,
Benni.