How to prevent Audacity from opening each track in a new window?

I’m using Linux Mint 17 and Audacity 2.0.5
I tried to open or import about 30 tracks. They are opend in 30 windows! In windows 10, all the tracks open in one window. Why Audacity behaves like that in linux? How can I solve it?

Okay, I knew the answer.
To import a file into the same project, I should use File > Import > Audio.

I should NEVER use: File > Open because it opens the file in a new window.

Pleased to see that you’ve solved the problem.

The “Open” command is primarily for opening “projects”. When you select and audio file with the “Open” command, it opens a new project and imports the selected file into it, so if you select multiple files, it opens a new project for each one. On the other hand, the “Import” command imports audio files into the current project.