Graham,
No one has up come with anything, I certainly aren't aware of a standard accelerator of any OS to navigate between folders.
The reason why not is you are probably only considering this case...
VBOX
FOLDER
...
END
FOLDER
...
END
END
... where it would be trivial to move from one folder to the next. However consider the case where folders are nested e.g.
VBOX
FOLDER
PAGE
FOLDER
PAGE
FOLDER
...
END
END
PAGE
FOLDER
...
END
END
...
END
...
END
END
FOLDER
PAGE
FOLDER
PAGE
FOLDER
...
END
END
PAGE
FOLDER
...
END
END
...
END
...
END
END
END
... suddenly moving from one folder to the next can have all sorts of ramifications, and you can understand wthy Microsoft et al hasn't assigned an accelerator to do it.
If your issue is more with a simple structure than the problem may be restated to be put more simply, can you create an action to jump between child elements of a VBOX or HBOX. In which case you can probably create a function to read the AUI Dom Tree and determine the first fieldname in the next or previous child element of a VBOX or HBOX relative to the current field, and then use Dialog.nextFIeld()
https://4js.com/techdocs/genero/fgl/devel/DocRoot/User/ClassDialog.html#nextField e.g.
ON ACTION jumpnext
LET fieldname = get_first_field_of_next_child(FGL_DIALOG_GETFIELDNAME())
IF fieldname IS NOT NULL THEN
CALL DIALOG.nextField(fieldname)
CONTINUE DIALOG
END IF
FUNCTION get_first_field_of_next_child(fieldname)
-- get node of current field
-- find parent vbox, hbox node
-- get next sibling of parent vbox, hbox node
-- find first child widget, either first descendant or lowest tabindex
RETURN next_fieldname
END FUNCTION
Hope that helps
Reuben