Added some missing defines.

include/dinput.h

diff --git a/include/dinput.h b/include/dinput.h
index f5b5149..50f6c54 100644
--- a/include/dinput.h
+++ b/include/dinput.h
@@ -1582,6 +1582,10 @@
 #define DIMOFS_BUTTON1 (FIELD_OFFSET(DIMOUSESTATE, rgbButtons) + 1)
 #define DIMOFS_BUTTON2 (FIELD_OFFSET(DIMOUSESTATE, rgbButtons) + 2)
 #define DIMOFS_BUTTON3 (FIELD_OFFSET(DIMOUSESTATE, rgbButtons) + 3)
+#define DIMOFS_BUTTON4 (FIELD_OFFSET(DIMOUSESTATE2, rgbButtons) + 4)
+#define DIMOFS_BUTTON5 (FIELD_OFFSET(DIMOUSESTATE2, rgbButtons) + 5)
+#define DIMOFS_BUTTON6 (FIELD_OFFSET(DIMOUSESTATE2, rgbButtons) + 6)
+#define DIMOFS_BUTTON7 (FIELD_OFFSET(DIMOUSESTATE2, rgbButtons) + 7)
 
 #ifdef __cplusplus
 extern "C" {