where is the Files ???

- when i click in the files icon don't see the Files window... i tried to move it to another workspace just to test and i never more see it again..

It seems your window manager is making some strange things to the files widget or any other that gets moved to another workspace (desktop?). Which desktop environment is that? I'll assume gnome as its the ubuntu default. I must say that I'm no fan of gnome, quite the contrary :) but in any case there should be a way to fix this. As I have no (personal) way to reproduce the problem, would you please trye whether switching the View/Options.../Display/Keep tool windows always on top option makes it any difference?

[UPDATE:] If all else fails, try editing the configuration file (~/.config/rncbc.org/Qtractor.conf) while you are NOT running qtractor and delete the line that starts with DockWindows... and rerun.

- in the "Files window" why don't put a new option in low (where midi and files is) like a Favorite Samples folder ..

Well, the Files widget serves as a way to organize your audio sample and MIDI sequence files at your own discretion. I know is not the same as a "Favorites" folder, but you can have file groups as folders for you to organize your files. Think of it as the "Files" window is already your session "Favorites" altogether.

- in the piano.. when we are in the "write mode" when we click with the right button it can delete the note...

It is not the first time I argue about the usefulness of this eraser mode or whatever, which I seem to think as yet another annoyance. Right-clicking is most seen to bring a context-menu up for options. Ok, it might be just me, personally again, but let's remember that the official way to delete events is through regular and generic multi/single-selection and pressing the Delete key :).

- in the piano.. in the write mode.. he can record the last size of the note and when we put it we don't need to resize it anymore and when it are selected we can move it to left right....

I'm afraid I find that annoying myself, on my own workflow, when doing some clicky-de-click editing. In fact the code to make that was commented out long ago. I still prefer the current way of having the notes sized from the current snap/beat setting. However, there's always a chance we can agree upon some user configuration option ;)

but the qtractor is developed in C++ only? if i wish to start helping coding , for where i could start ? and what i need?

Yes, it's all old-school C++, that meaning it's more to C-style than super-duper modern high-energy sweetned C++. I can't really tell where to start, but I would suggest you could browse into Jasmin Blanchette's book "C++ GUI Programming with Qt 4", for instance and see if your hair raises that little bit ;) That and more hair raising reading here

Cheers