Interface consistency is one of those things that, if done correctly, should go unnoticed. I've slowly been working on a new interface for a side project and thought it'd be a treat to share my approach.
Interfaces evolve based on the needs of people using them. Each task may require a different element. Common elements include buttons, dialogs, drop-downs, select boxes, checkboxes, input fields, etc. These elements are like notes in a composition seeking harmony.
To ensure harmony I'll arrange my elements on a single canvas and show the different levels of interaction. By doing this I can easily spot inconstancies. This also helps build a style guide for future elements and interaction.
This is not groundbreaking by any means. Just thought I'd share and help promote the practice :)