TYPO3 Core

There are some usability / wording issues of the new EM:

- Tab "Local Extension List" is misleading as there are local extensions which are not the same here because this lsit shows also system exts

- cursor:pointer is missing on several places: arrow to open extension details / extension title

- if opening an extension info, already opened windows should be closed

- my extension shows "Error parsing json response: null"

- Check Validity seems not to work?

- Check Validity can't be stopped if there seems to be an error

- upload extension: no info if file is not a t3x besides a red line.

- upload extension: selecting a file shows "C:\fakepath\" as directory?? wtf?

- wrong escaping with entries in EM like username, repository name. "\fo" is transformed to "\\fo"

- Extension list in "Translation handling": strange order. also strange order of languages

- Local extension list misses version as seperate column

- "remote repository" what should this mean? my TYPO3 is already on a remove machine... ?

- "remote repository" > is there a sense in showing 2200 extensions onloading? will anyone use the pagebrowser to search for an ext

- "remote repository" > how can I update repo??

(issue imported from #M17015)