* `do_outliner_item_rename()` enables the rename mode for the item under the
cursor. Issue is, collapsed children end up having stored the same coordinate
as their parent, so they too would get the rename mode enabled (there is no
early-exit that would hide this).
* The items displayed as inline icons do get the proper coordinates of the
icons, so they are not mistaken as being under the cursor.
After rBb077de086e14, the Outliner tree is rebuilt less often, so the
coordinates are cleared less often too.
As far as I can see we can always clear coordinates of invisible items now. No
code seems to depend on keeping the old coordinates anymore.
5129e2e042