Created attachment 114198 [details]
Patch for gcc4 build

Give this one a try.

Hey Ignacio, I was looking at your fix:
 
-  Pointer_val(*glob_root) = NULL;
+  Field(*glob_root, 1) = NULL;

and found that it still throws a (harmless?) warning:

ml_panel.c: In function 'weak_notify':
ml_panel.c:131: warning: assignment makes integer from pointer without a cast

Is there some reason the folloning is incorrect?

 static void weak_notify(gpointer data, GObject *applet)
 {
   value *glob_root = data;
-  Pointer_val(*glob_root) = NULL;
+  *glob_root = (value)NULL;
   ml_global_root_destroy(glob_root);
 }

Casting has always been my least favorite area of C so I thought running it by
you first would be best.

Your code is incorrect because it replaces the entire contents as opposed to jus
that one field. You can assign 0 instead of NULL if you want to ditch that last
warning.

Thanks, I'll change it to this:
  Field(*glob_root, 1) = 0;

changed arch to all. unison rebuild fails because of this.

Hmm - the value type is defined in <caml/mlvales.h>:
  typdef long value;
So that means glob_root is pointing at a 64 bit integer (on x86_64).  This seems
to be the most expressive way to put it:
  Field(*glob_root, 1) = (long)NULL;
Does that seem right to you?

Honestly, I don't know enough about Ocaml's internals to say yes or no wrt that.
If it works, then feel free to use it.

Patch added and submitted for build

This has been built -- 2.4.0-5