IntelliJ IDEA 12.1.0 Web Help
Some features described here are available in Ultimate edition only.
You can limit the scope of your DSM to the selected rows.
Only these will remain in the new matrix.
In the DSM view, select the rows to remain.
Right-click the selected rows and choose Limit Scope To Selection in the menu.
The limited scope will be opened in a new tab within the DSM view.