[LyX/master] Fix Undo with search-string-set

[Juergen Spitzmueller]

commit 672ff0963443fe81852c1b8d70740a74cfda25bd
Author: Daniel Ramoeller <d.lyx at web.de>
Date:   Thu Feb 18 08:05:15 2021 +0100

    Fix Undo with search-string-set
    
    Makes it possible to use the find combobox's internal undo feature to undo a set search string.
---
 src/frontends/qt/GuiSearch.cpp |    7 ++-----
 1 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/frontends/qt/GuiSearch.cpp b/src/frontends/qt/GuiSearch.cpp
index 11cda70..323ac8a 100644
--- a/src/frontends/qt/GuiSearch.cpp
+++ b/src/frontends/qt/GuiSearch.cpp
@@ -322,11 +322,8 @@ void GuiSearchWidget::findBufferChanged()
 	docstring search = theClipboard().getFindBuffer();
 	if (!search.empty()) {
 		LYXERR(Debug::CLIPBOARD, "from findbuffer: " << search);
-#if QT_VERSION > 0x050000
-		findCO->setCurrentText(toqstr(search));
-#else
-		findCO->setEditText(toqstr(search));
-#endif
+		findCO->lineEdit()->selectAll();
+		findCO->lineEdit()->insert(toqstr(search));
 	}
 }