IMPORTANT: This issue has been caused by the recent attempt to fix T213704 using the Mutation Observer API. There is a better version of the library which does not have this issue, see {T244994} for details on reconciling current versions
When any step in a tour uses the `attachTo` property for positioning the pop up, the **back button** shows both the next and the previous slide at the same time.
For steps which do not use the `attachTo` property, you can navigate forward and back normally without any problem.
**Steps to Reproduce:**
# Load the items Wikidata tour - https://www.wikidata.org/w/index.php?title=Q16943273&tour=wbitems
# Verify that the back button works perfectly up to and including the "Item Pages" step (step number 5)
# Once you reach the "Labels" step (step number 6), press the back button
**Actual Results:**
After clicking the back button on step 6 (the first step to include an `attachTo` property), the pop ups for both step 5 and step 7 are shown at the same time.
The same can be seen in subsequent steps in the tour, as well as on step 3 onward in the [[ https://www.wikidata.org/w/index.php?title=Q17339402&tour=wbstatements | statements tour ]]
**Expected Results:**
Only the previous step should be displayed when clicking the back button, step 5 in this case.
Step 7 should only be revealed after clicking the forward button (or completing an action that skips to the next slide)