Hi Nadeem,
AX2012 as you know provides the facility of advanced filter / sorting in it's list pages. When you open the "All Purchase orders" under AP >> common >> Purchase orders.
In the Top left corner, you will be able to see in Green font "All Purchase orders (Unsaved filter)". You filter the data from Filter >> Advanced filter / sort and click Save as filter or Save as Cue. (one time activity)
the next time you want to see a list of Purchase order in Cancelled status, just select the saved query. If you have saved it as a cue you can see it in your Role center page as well.
A customization really not necessary for this.
thanks,
Manish