How can I open a Simulink model from current directory and its subsystems in the same window?

Each time I double click on a Simulink model from my directory, several windows of Simulink Editor appear, one with the "master" model and the others with all the subsystems.

I'm using Matlab2014a for Mac.

Could someone please suggest me how can I open only the "master" model? In addiction, there is a faster way to open a subsystem in new tab by double click (without right click --> open in new tab)?

Regards.