In SDL Web 8.5/SDL Tridion Sites 9.x, unable to create a new component in the main pane when there is no empty space via right-click context menu

- After upgrading from Tridion 2013 SP1 to SDL Web 8.5 or SDL Tridion Sites 9.0/9.1/9.5, it is no longer possible to create a new component from the main pane when there is no empty space in main pane.

When clicking in an empty space, the New context menu is available.

- When using Tridion 2013 SP1 or earlier versions, it was possible to use the New context menu regardless of whether there was no empty space or not in main pane.
 

The UI change is intentional and expected in Web 8 and later product versions.  Also see KB article In SDL Web, unable to create component from left navigation pane