There are some things I would like to learn about, maybe if you can get some ideas and make some tutorials someday.
Or maybe someone knows some sites that explain these things very well.
I think this is a good list for everyone wanting to create bigger games in the future, when I can think of more I will put them in here!
Most things are meant for 2D programming, the list is not in any particular order.

Game programming related topics:
- Game State Management (What is the difference with scenes?)
- Scene Management (What is the difference with Game state?)
- Object/Entity Management(How they know each other!!!, etc...)
- Object interaction (followup from management, how to get objects interact with each other)
- Input Controller(management for input, etc...)
- GUI programming (creating Menu's, HUD's, etc...)
- 2D game Math (Vector math, etc...)

- Particle Engine (Emitter, match, particle management, etc...)
- Design Patterns for game programming (Logical examples where they can be used, Factory, Singleton, etc...)
- Content Management (The use of ID's, stores sprites, sounds, etc...)

Good ideas Saido! Some things will definitely be addressed in the future, including your GUI suggestion. I'll keep all these things in mind for future tutorials.

i would like to see a tutorial about textbox...

you forgot about AI!

good subjects would be: finite state machines, path finding, decision making and scripting.

cheers!

Some things coming down the pipe:

- Lua tutorials (integration, and using Lua itself)
- A* pathfinding
- Application States (game states)
- GUI framework
- SQLite

I did want to say though, regarding "Object/Entity Management(How they know each other!!!, etc...)", you can do that with Collision Events. Anything beyond that should be done with methods for requesting data - i.e., "What Entities are on the same map as me?", "What entities are in my view?"