Known issue: pressing the X button on the sidebar will not register as a
"sidebar closed" event which means re-opening the sidebar will need 2 clicks
on the toolbar button.
However, a similar add-on (TreeStyleTab) doesn't exhibit the same issue; could there be a fix/workaround?
Per a8760b1:
However, a similar add-on (TreeStyleTab) doesn't exhibit the same issue; could there be a fix/workaround?