asymetric Meta keys with MacVim

asymetric-MacVim-meta.diff

diff --git a/src/MacVim/MMTextViewHelper.m b/src/MacVim/MMTextViewHelper.m
index 4d10432..42f311b 100644
--- a/src/MacVim/MMTextViewHelper.m
+++ b/src/MacVim/MMTextViewHelper.m
@@ -22,6 +22,9 @@
 #import "MMWindowController.h"
 #import "Miscellaneous.h"
 
+// asymetric meta keys
+#define NSLeftAlternateKeyMask  (0x000020 | NSAlternateKeyMask)
+#define NSRightAlternateKeyMask (0x000040 | NSAlternateKeyMask)
 
 // The max/min drag timer interval in seconds
 static NSTimeInterval MMDragTimerMaxInterval = 0.3;
@@ -165,7 +168,8 @@ KeyboardInputSourcesEqual(TISInputSourceRef a, TISInputSourceRef b)
     // ASCII chars in the range after space (0x20) and before backspace (0x7f).
     // Note that this implies that 'mmta' (if enabled) breaks input methods
     // when the Alt key is held.
-    if ((flags & NSAlternateKeyMask) && [mmta boolValue] && [unmod length] == 1
+    if (((flags & NSLeftAlternateKeyMask) == NSLeftAlternateKeyMask)
+            && [mmta boolValue] && [unmod length] == 1
             && [unmod characterAtIndex:0] > 0x20
             && [unmod characterAtIndex:0] < 0x7f) {
         ASLogDebug(@"MACMETA key, don't interpret it");