Not currently sure how this was designed to work.I think I can still imagine how tabbing through the levels could, sometimes, be useful, if it was available, though.
Anyway, if someone knows it is a bug and comments then i'll report it.
This shortcut list (excellent work by Véronique [Updated on July 17, 2022]): (http://www.sweethome3d.com/blog/2019/03 ... tcuts.html)
states:
Windows/Linux/Mac
Action
Select a level in a plan
Keyboard shortcut
Arrows ← → with the focus on tabs
Actual behaviour in SH3D (7.2) on Win 7&10:
Clicking on a level tab followed by a keyboard arrow key does not appear to do anything.
Double clicking on a level tab (obviously) displays the "Modify level" dialog. When any of "close/ok/cancel" in that dialog are then pressed and, subsequently, a left/right keyboard arrow is pressed then the other levels (but only those displayed on the same line as the level originally chosen) are stepped through.
As a note:
double clicking to activate the behaviour is inconvenient
stepping through a single line of displayed levels only makes the functionality very limited (for my use case, useless).