When Print button (eg on Dashboard) is clicked this sets
$rootScope.isBeingPrinted = true;
Which is then used in some of the directives such as pivotTable, bhamniObservation but not in all the display controls such as visitTable, or the other examples of custom display controls.
This will help to customize the behavior of display controls in printing such as dashboard printing.
e.g. To avoid printing of Navigation Link Display Control if included on dashboard change this to
<section ng-if="!$root.isBeingPrinted" class="navigation-links-wrapper">
Is it default feature of Angular right?
Yes, of course if you are referring to accessing rootScope vars.
I mentioned this here as the Bahmni wiki pages does not mention about customizing / altering Dashboard print behavior.