[LyX/master] Do not insert non-rpintable characters (such as ASCII control characters)

[Juergen Spitzmueller]

commit 4ba17c90a03fc5b50612a20604eba426f7dedcf6
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Tue May 5 14:23:24 2015 +0200

    Do not insert non-rpintable characters (such as ASCII control characters)
    
    Fixes: #5704.

diff --git a/src/frontends/qt4/GuiApplication.cpp 
b/src/frontends/qt4/GuiApplication.cpp
index 4822e59..160df4a 100644
--- a/src/frontends/qt4/GuiApplication.cpp
+++ b/src/frontends/qt4/GuiApplication.cpp
@@ -69,6 +69,7 @@
 #include "support/lassert.h"
 #include "support/lstrings.h"
 #include "support/lyxalgo.h" // sorted
+#include "support/textutils.h"
 #include "support/Messages.h"
 #include "support/os.h"
 #include "support/Package.h"
@@ -2131,6 +2132,12 @@ void GuiApplication::processKeySym(KeySymbol const & 
keysym, KeyModifier state)
                // if it's normal insertable text not already covered
                // by a binding
                if (keysym.isText() && d->keyseq.length() == 1) {
+                       // Non-printable characters (such as ASCII control 
characters)
+                       // must not be inserted (#5704)
+                       if (!isPrintable(encoded_last_key)) {
+                               LYXERR(Debug::KEY, "Non-printable character! 
Omitting.");
+                               return;
+                       }
                        LYXERR(Debug::KEY, "isText() is true, inserting.");
                        func = FuncRequest(LFUN_SELF_INSERT,
                                           FuncRequest::KEYBOARD);