Content jumps back and forth when trying to move a core field into a repeating element.

[PKuhlmay]

I have the following configuration:

• a repeating element
• a header inside the repeating element
• a subheader inside the repeating element
• a header, with the core field "header".
  
  When I now try to move the field with the core-field header inside the repeating element, the content bounces up and down very fast.
  I know that it won't be possible to have an element inside the repeating content element with any of the core fields, so it should not be possible to move this one inside the repeating element.
  But this behavior looks very strange. I think the mask-app tries to move it "before" or "after" the repeating element.

MaskDragDrop.mov

TYPO3 12.4.6
mask v8.3.5

[nhovratov]

Hey @PKuhlmay, yes I know this behaviour. I can't fix this, because this is how Sortable behaves. I added a check, whether the field is allowed to be placed there. If not, Sortable just wont even show the drag/drop preview, but will jump to the next possible allowed gap, which triggers this glitchy view in your video. It would be cool, if it would just restore itself to the last position (this is how it worked in old jquery based Mask with jquery-ui).

If you have any suggestion, how this could be improved, I would be very glad.