This cost me more than an hour (probably my fault, I am sure it is somewhere in the docs)…
Positioning elements on a form via the gui and/or in the properties bar works relative to the upperleft corner (0, 0) of the form. No matter if this is a footer, body, header of whatever alternative part we have.
But now, do this via scripting and you have to do the positioning relative to the upperleft corner of the part the element is on…
Is this intentional and/or can this be changed?