Make it so the "Inbox" actually shows ALL tasks so is the Master ToDo List.
The Inbox should show all Tasks. Otherwise, there's no screen to use to review all tasks to make sure you're not missing anything.
Hugo van den Berg commented
This is entirely against the GTD philosophy. You should move everything regularly AWAY from your Inbox to their designated locations depending on the next actions, and review those lists separately, possibly on different occasions. Even if you'd need an overview of all open tasks it should be in a separate list, and definitely NOT in the Inbox.