TYPO3 Core

The JS lookup which detects the target page ID does a very loose lookup in the entire dom and catches what appears to be a page tree DOM element, then it reads the "data-page" attribute from it indiscriminately.

This causes two things:

• The DataHandler command map that is received contains the page title instead of the ID
• Anything that assumes an integer is provided and does casting, ends up with pid=1 which may not be a valid page and most likely is not the desired target page

While the surrounding code then fixes this (by simply ignoring this value...) it does mean that drag and drop does not work predictably in some DataHandler contexts (inability to read the actual page UID from anywhere).

Using the drop-target-relative parent's data attribute instead completely solves the problem. Does not affect 8.7.