table swap menu entries are not displayed in LyX 1.5.4

[Uwe Stöhr]

stdmenus.inc has these two useful entries:

Item "Swap Rows|S" "tabular-feature swap-row"
and
Item "Swap Columns|w" "tabular-feature swap-column"

But in LyX they are not shown in LyX 1.5.4 and LyX 1.6svn. Am I doing something 
wrong?

regards Uwe