tblr row to row distance when using \cline

Question

it seems that when using \cline or \SetHline the rows below are displaced downward by the value of the horizontal line inserted. I have three tables in three columns in a beamer slide and at the same height. I tried to compensate with rowsep the row to row distance in one of the other tables but it does not seem to do what i want. I just want to have the row to row distance equal for all tables, despite using any \cline or else in some tables.

\documentclass[aspectratio=169,t]{beamer}

\mode<presentation>
\usetheme{moloch}
\usepackage{tabularray,blindtext}

\newcommand{\titles}[1]{{\bfseries #1\par\vspace{.6em}}}

\setlength{\parindent}{0pt}

\begin{document}
\begin{frame}{aaa}
  \begin{columns}
    \begin{column}{.3\pagewidth}
      \titles{first column}
      \begin{tblr}{colspec={lll},rowsep={2pt}}
        a & b & c\\
        d & e & f\\
        g & h & i\\
        j & k & l\\
        m & n & o\\
      \end{tblr}
      
    \end{column}
    \newlength\mytmp
    \setlength{\mytmp}{6em}
    \begin{column}{.3\pagewidth}
      \titles{second column}
      \begin{tblr}{lll}
        a & b & c\\
        \cline[2pt,blue]{-}
        d & e & f\\
        g & h & i\\
      \end{tblr}

    \end{column}
    
    \begin{column}{.3\pagewidth}
      \titles{third column}
      \begin{tblr}{lll}
        a & b & c\\
        d & e & f\\
      \end{tblr}
    \end{column}
  \end{columns}
  
\end{frame}
\end{document}

Answer 1

Try adding row{1}={belowsep=0pt} to the options of the second table. And be sure to replace \pagewidth with \textwidth.

\documentclass[aspectratio=169,t]{beamer}

\mode<presentation>
\usetheme{moloch}
\usepackage{tabularray}

\newcommand{\titles}[1]{{\bfseries #1\par\vspace{.6em}}}

\setlength{\parindent}{0pt}

\begin{document}
\begin{frame}{aaa}
  \begin{columns}
    \begin{column}{.3\textwidth}
      \titles{first column}
      \begin{tblr}{colspec={lll},rowsep={2pt}}
        a & b & c\\
        d & e & f\\
        g & h & i\\
        j & k & l\\
        m & n & o\\
      \end{tblr}
    \end{column}

    \begin{column}{.3\textwidth}
      \titles{second column}
      \begin{tblr}{colspec={lll},rowsep={2pt},row{1}={belowsep=0pt}}
        a & b & c\\
        \cline[2pt,blue]{-}
        d & e & f\\
        g & h & i\\
      \end{tblr}
    \end{column}

    \begin{column}{.3\textwidth}
      \titles{third column}
      \begin{tblr}{colspec={lll},rowsep={2pt}}
        a & b & c\\
        d & e & f\\
      \end{tblr}
    \end{column}
  \end{columns}
\end{frame}
\end{document}

Answer 2

You could use tikz to add a line to your table, which won't influence the table:

\documentclass[aspectratio=169,t]{beamer}

\usetheme{moloch}
\usepackage{tabularray}
\UseTblrLibrary{tikz}
\usepackage{tikz}

\newcommand{\titles}[1]{{\bfseries #1\par\vspace{.6em}}}

\begin{document}
\begin{frame}
\frametitle{aaa}
  \begin{columns}
    \begin{column}{.3\textwidth}
      \titles{first column}
      \begin{tblr}{colspec={lll},rowsep={2pt}}
        a & b & c\\
        d & e & f\\
        g & h & i\\
        j & k & l\\
        m & n & o\\
      \end{tblr}
      
    \end{column}
    \newlength\mytmp
    \setlength{\mytmp}{6em}
    \begin{column}{.3\textwidth}
      \titles{second column}
      \begin{tblrtikzabove}
      \draw (1-1.south west) -- (1-3.south east);
      \end{tblrtikzabove}%
      \begin{tblr}{lll}
        a & b & c\\
        d & e & f\\
        g & h & i\\
      \end{tblr}

    \end{column}
    
    \begin{column}{.3\textwidth}
      \titles{third column}
      \begin{tblr}{lll}
        a & b & c\\
        d & e & f\\
      \end{tblr}
    \end{column}
  \end{columns}
  
\end{frame}
\end{document}