In pre 4.0 versions of Zabbix we could assign templates to hosts/groups directly from the "Templates" tab in template editor.

3.4 - Creating a template:

In 4.0.0beta1 this functionality is not available and the only way to mass-assign templates to hosts is to filter hosts in "Hosts" screen and use "Mass update".

This is a poor replacement, since there is no way to actually see all hosts linked to a template.

Please, restore this functionality to pre 4.0 state.