Added LVKF_* defines.

diff --git a/include/commctrl.h b/include/commctrl.h
index 795837a..e3c6b81 100644
--- a/include/commctrl.h
+++ b/include/commctrl.h
@@ -3069,6 +3069,10 @@
     UINT uKeyFlags;
 } NMITEMACTIVATE, *LPNMITEMACTIVATE;
 
+#define LVKF_ALT     0x0001
+#define LVKF_CONTROL 0x0002
+#define LVKF_SHIFT   0x0004
+
 typedef struct tagLVDISPINFO
 {
     NMHDR hdr;