[LyX/master] Do not hardcode launching of lyxpaperview script.

[Pavel Sanda]

commit 44ede7ef4b1603c70c74c02ab784c17e5d7053e2
Author: Pavel Sanda <sanda at lyx.org>
Date:   Mon Aug 24 15:10:14 2020 +0200

    Do not hardcode launching of lyxpaperview script.
---
 src/LyXRC.h                     |    2 +-
 src/frontends/qt/qt_helpers.cpp |    6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/LyXRC.h b/src/LyXRC.h
index 1f32fef..d795d34 100644
--- a/src/LyXRC.h
+++ b/src/LyXRC.h
@@ -245,7 +245,7 @@ public:
 	/// command to run chktex incl. options
 	std::string chktex_command = "chktex -n1 -n3 -n6 -n9 -n22 -n25 -n30 -n38";
 	// Name of external script, which searches for file corresponding to a 
-	// given citation. At this moment only script "lyxpaperview" is supported
+	// given citation. At this moment only script lyxpaperview[.py] is supported
 	// (search for pdf based on author+year), but we can generalize if requested.
 	// Citation context menu item "Open Citation Content" will be always enabled
 	// if the name of this script in nonempty (last resort when citation entry
diff --git a/src/frontends/qt/qt_helpers.cpp b/src/frontends/qt/qt_helpers.cpp
index 176267a..92ee029 100644
--- a/src/frontends/qt/qt_helpers.cpp
+++ b/src/frontends/qt/qt_helpers.cpp
@@ -24,6 +24,7 @@
 #include "FuncRequest.h"
 #include "Language.h"
 #include "LyX.h"
+#include "LyXRC.h"
 #include "LyXAction.h"
 #include "TextClass.h"
 
@@ -300,9 +301,12 @@ void showDirectory(FileName const & directory)
 void showTarget(string const & target){
 	LYXERR(Debug::INSETS, "Showtarget:" << target << "\n");
 	if (prefixIs(target,"EXTERNAL ")) {
+		if (lyxrc.citation_search_view.empty())
+			return;
 		string tmp,tar;
 		tar = split(target, tmp, ' ');
-		FuncRequest cmd = FuncRequest(LFUN_VC_COMMAND,"U . \"lyxpaperview " + tar + "\"");
+		FuncRequest cmd = FuncRequest(LFUN_VC_COMMAND,"U . \"" +
+		                  lyxrc.citation_search_view + " " + tar + "\"");
 		lyx::dispatch(cmd);
 		return;
 	}