Fix: on MS-Windows the "open with..." menu starts Vim without a file.

src/dosinst.c

@@ -1468,11 +1468,15 @@ register_openwith(
     HKEY hRootKey,
     const char *exe_path)
 {
-    LONG lRet = reg_create_key_and_value(
+    char	exe_cmd[BUFSIZE];
+    LONG	lRet;
+
+    sprintf(exe_cmd, "%s \"%%1\"", exe_path);
+    lRet = reg_create_key_and_value(
 	    hRootKey,
 	    "Applications\\gvim.exe\\shell\\edit\\command",
 	    NULL,
-	    exe_path);
+	    exe_cmd);
 
     if (ERROR_SUCCESS == lRet)
     {