Say for whatever reason, a site builder needs to replace a menu with another via the admin UI, while at the same time retaining the configuration (menu style and depth, style settings, visibility conditions):

  1. Add a new menu block in the same region.
  2. [add as many steps/clicks here as required to manually copy the configuration of the old menu block...]

...

n-2. ... n-1. Remove the old menu block n. Save the layout

...so basically the more complicated configuration the old menu block has, the more clicking a site builder needs to do in order to replicate the block configuration to the new menu block.

Compare the above to this:

  1. Edit existing menu block.
  2. Select another menu from a drop-down menu that lists all available menus.
  3. Save the menu block
  4. Save the layout
GitHub Link: 
https://github.com/backdrop/backdrop-issues/issues/3410
GitHub Issue #: 
3410