[LyX/master] For Mac OS: Additional check for Control and Meta modifier swap state. Starting with Qt 5 the modifiers aren't reported correctly for disabled swap. Until this is fixed it is corrected by reverting the modifier mask to check for.

[Stephan Witt]

commit 2a3b54d57b82748ad164b9471917d33cd247a929
Author: Stephan Witt <sw...@lyx.org>
Date:   Sat Oct 24 21:03:01 2015 +0200

    For Mac OS: Additional check for Control and Meta modifier swap state.
    Starting with Qt 5 the modifiers aren't reported correctly for disabled 
swap.
    Until this is fixed it is corrected by reverting the modifier mask to check 
for.

diff --git a/src/frontends/qt4/GuiKeySymbol.cpp 
b/src/frontends/qt4/GuiKeySymbol.cpp
index 54a4516..d058bce 100644
--- a/src/frontends/qt4/GuiKeySymbol.cpp
+++ b/src/frontends/qt4/GuiKeySymbol.cpp
@@ -11,6 +11,7 @@
 #include <config.h>
 
 #include "KeySymbol.h"
+#include "GuiApplication.h"
 
 #include "qt_helpers.h"
 
@@ -744,14 +745,24 @@ bool KeySymbol::operator==(KeySymbol const & ks) const
 KeyModifier q_key_state(Qt::KeyboardModifiers state)
 {
        KeyModifier k = NoModifier;
-       if (state & Qt::ControlModifier)
+#if defined(Q_OS_MAC) && QT_VERSION > 0x050000
+       /// Additional check for Control and Meta modifier swap state.
+       /// Starting with Qt 5 the modifiers aren't reported correctly.
+       /// Until this is fixed a correction is required.
+       const bool dontSwapCtrlAndMeta =
+               
frontend::theGuiApp()->testAttribute(Qt::AA_MacDontSwapCtrlAndMeta);
+#else
+       const bool dontSwapCtrlAndMeta = false;
+#endif
+
+       if (state & (dontSwapCtrlAndMeta ? Qt::MetaModifier : 
Qt::ControlModifier))
                k |= ControlModifier;
        if (state & Qt::ShiftModifier)
                k |= ShiftModifier;
        if (state & Qt::AltModifier)
                k |= AltModifier;
 #if defined(USE_MACOSX_PACKAGING) || defined(USE_META_KEYBINDING)
-       if (state & Qt::MetaModifier)
+       if (state & (dontSwapCtrlAndMeta ? Qt::ControlModifier : 
Qt::MetaModifier))
                k |= MetaModifier;
 #else
        if (state & Qt::MetaModifier)