to_global has Problem with different cell-sizes

I have multiple meshes in different sizes and cell sizes.

The xy-plane (z-axis) works as desired. But slcf/slices.py:to_global returns a tuple for axis x and y instand of numpy.ndarray.
The first element contains the numpy.ndarray of the finder mesh, while the second element contains the numpy.ndarray of the coarser mesh. It would be nice, if all axis behave same and create only one result.

Problem illustrated:
z|x
y|-