Put quotes around the gvim.exe path for the "Open with" menu entry.
diff --git a/src/dosinst.c b/src/dosinst.c
index 979d6fe..84d171b 100644
--- a/src/dosinst.c
+++ b/src/dosinst.c
@@ -1463,7 +1463,7 @@
     char	exe_cmd[BUFSIZE];
     LONG	lRet;
 
-    sprintf(exe_cmd, "%s \"%%1\"", exe_path);
+    sprintf(exe_cmd, "\"%s\" \"%%1\"", exe_path);
     lRet = reg_create_key_and_value(
 	    hRootKey,
 	    "Applications\\gvim.exe\\shell\\edit\\command",