Edit ID on z-stacks - "Z:[z.unit]" label is fixed to 0.00um

[Rdornier]

Bug report

Describe the bug
The label "Z:[z.unit]" updates to 0.00um and is not further updated when you copy-paste an image and edit its id (the new image has the same number of xyczt). This issue happens on the copied images, even if you delete previous labels and add them again.
However, this issue does not happen if you replace "unit" by "pixel" in the label field.
Edit: Related issue #512

To Reproduce

1. Open a new figure
2. Import an z-stack
3. Select some slices
4. Add "Z:[z.unit]" label (You need to manually replace "pixel" by "unit")
5. Copy-Paste the slices
6. Select the new coipes
7. Edit their ID with the ID of a new stack (with same number of xyczt => can be the same image ID as well)
8. All the labels are updated to "Z: 0.00 um"
9. If you change the displayed slice, the label doesn't update anymore

Expected behavior
The label should be updated correctly regarding the displayed slice.

Screenshots

Desktop :

• Software: OMERO.figure
• version: 6.0.0

ping @romainGuiet

[Rdornier]

This issue should be fixed in the PR #518.
The z-step and z-unit were added to the minimal attributes to transfer when setting a new ID.