When multiple nodes (Frame nodes included in the selection) are scaled/
rotated, the TransData location and center can get "wrong" due to the
fact that Frame nodes dont only use `locx`/`locy` for their
representation while drawing, but also `offsetx`/`offsety`.
So in order to use the "real" top-left corner in the transform system,
we have to respect `offsetx`/`offsety` when creating/flushing transform
data.
In addition to the file in the report, this patch was also tested to work
well with nested Frame nodes.
Philipp Oeser