Open/Handle Multiple files

TF Must be capable to handle more than 1 file open, this issue describe how it will be done.

The default way is create a notepad widget, then each tab is a opened file, this issue have to handle:
- Open a file
- Close file (using the button in tab, and close with the middle button)
- Open a opened file 
- Save a file with other name
- Change tab order
