[LyX/master] Fix bug #12721.

[Richard Kimberly Heck]

commit 211554d0df4b76b63217f67077992b5b258cc549
Author: Daniel Ramoeller <d.lyx at web.de>
Date:   Thu Mar 30 16:12:08 2023 -0400

    Fix bug #12721.
---
 src/insets/InsetExternal.cpp |    6 ++++++
 src/insets/InsetExternal.h   |    3 ++-
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/src/insets/InsetExternal.cpp b/src/insets/InsetExternal.cpp
index 92308db..0581d2e 100644
--- a/src/insets/InsetExternal.cpp
+++ b/src/insets/InsetExternal.cpp
@@ -933,4 +933,10 @@ string InsetExternal::params2string(InsetExternalParams const & params,
 	return data.str();
 }
 
+
+docstring InsetExternal::toolTip(BufferView const &, int, int) const
+{
+	return from_utf8(params().filename.onlyFileName());
+}
+
 } // namespace lyx
diff --git a/src/insets/InsetExternal.h b/src/insets/InsetExternal.h
index f124445..ce71c94 100644
--- a/src/insets/InsetExternal.h
+++ b/src/insets/InsetExternal.h
@@ -177,7 +177,8 @@ private:
 	bool isPreviewed() const;
 	/// Do we have the right renderer (button, graphic or monitored preview)?
 	bool isRendererValid() const;
-
+	///
+	docstring toolTip(BufferView const & bv, int x, int y) const override;
 	/// The current params
 	InsetExternalParams params_;
 	/// The thing that actually draws the image on LyX's screen.