TabLt               <Shift Tab>
    -------------------------------------------------------------------------

    Positions the cursor at the previous tab position, as defined by the
    tab width.  If in Insert mode, the text to the right of, and
    including the cursor position, also shifts left.

    When pressed while the cursor is inside a marked block and insert
    mode is on, shifts the entire block by the current cursor tab width.

    The ability to Tab whole blocks was added in QEdit 2.1