Different behavior of Arduino IDE on Linux OsX and Win7

I have a project consisting of several files. I program OOP style. The files are individual classes.

  1. On OSX (Mac) everything works as it should.
  2. On Linux, you can not open the files in tabs, IDE requires a move to separate folders. Or nothing.
  3. Win7 Although the project will open in the tabs, but at compile time error occurs, the class of the other files do not exist.

I transfer a project using a shared cloud disk (Mega). I use Arduino IDE version 1.6.5

I'm doing something wrong or is this normal behavior IDE and dividing the project into multiple files is a bad idea? I'm sorry, I'm a programmer, but Arduino just getting started.