How can I fill blank spaces with \dotfill in \tabbing environment? How can I adjust the length of \dotfill?
\documentclass{article}
\begin{document}
\begin{tabbing}
\hspace*{3cm}\=\hspace*{2cm}\= \kill
column1a \> column2a \> column3a \\
column1b \> column2b \> column3b
\end{tabbing}
\end{document}


