From fcc56daa653760b1a6e1abc87081291b09d91e81 Mon Sep 17 00:00:00 2001
From: Jan Benda <jan.benda@uni-tuebingen.de>
Date: Thu, 4 Mar 2021 12:46:39 +0100
Subject: [PATCH] action aware \messagebox

---
 beamerthemelines.sty | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/beamerthemelines.sty b/beamerthemelines.sty
index 28e3914..11a803d 100644
--- a/beamerthemelines.sty
+++ b/beamerthemelines.sty
@@ -486,19 +486,19 @@
     {\usebeamercolor[fg]{message symbol}\usebeamertemplate{message symbol}}%
     \strut\insertmessage
   \end{beamercolorbox}
-  \nointerlineskip%
   \ifbeamercolorempty[fg]{message line bottom}{}{%
+    \nointerlineskip%
     \begin{beamercolorbox}[wd=\columnwidth,hd=#2]{message line bottom}
       \rule{\columnwidth}{#2}
-    \end{beamercolorbox}
-    \nointerlineskip}%
+    \end{beamercolorbox}}%
+  \medskip
 }
 
 \setbeamertemplate{message}[lines]{0.5pt}{0.5pt}
 
-\newcommand{\messagebox}[1]{%
-  \def\insertmessage{#1}%
-  \usebeamertemplate*{message}
+\newcommand<>{\messagebox}[1]{%
+  \only#2{\def\insertmessage{#1}%
+    \usebeamertemplate*{message}}
 }