[LyX/2.3.x] Fix typo.

[Juergen Spitzmueller]

commit 2b927cbc2ee79f1d1f8a125f4d1a88162a1e5dfa
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Wed Dec 20 12:17:04 2017 +0100

    Fix typo.
    
    This had the effect that for file dialogs supposed to use two buttons,
    only the second one was displayed, while file dialogs supposed to use
    one button did not have a button at all.
    
    Candidate for 2.3.x and 2.2.x.
    
    (cherry picked from commit 74607702a585fd68bdf6b9cda668421a4ed06f3e)
---
 src/frontends/qt4/GuiPrefs.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/frontends/qt4/GuiPrefs.cpp b/src/frontends/qt4/GuiPrefs.cpp
index 7f55a4d..4681dd3 100644
--- a/src/frontends/qt4/GuiPrefs.cpp
+++ b/src/frontends/qt4/GuiPrefs.cpp
@@ -112,7 +112,7 @@ QString browseFile(QString const & filename,
                lastPath = fallback_dir;
 
        FileDialog dlg(title);
-       dlg.setButton2(label1, dir1);
+       dlg.setButton1(label1, dir1);
        dlg.setButton2(label2, dir2);
 
        FileDialog::Result result;