Version:           1.7.0 (using KDE 4.5.90) 
OS:                Linux

With the tags tree, either in the "Tags" sidebar on the left or the "Tag Filters" sidebar on the right, you can right-click in the area with tags in order to add a new sub-tag to the tag you clicked on.  However, you cannot right-click on the area below the list of tags.  This makes it hard to make a new root-level tag.

Reproducible: Always




You also cannot right-click below the albums tree in My Albums, but since you cannot make a new root-level album this does not matter as much.