When selecting a specific area of the T-workflow, all the objects (i.e. blocks and connections) within them will be chosen unless the "select blocks only" or "select connections only" options are enabled.
Moreover, by holding the [Control] key and clicking on different objects, it will be possible to add/remove more things to the selection. Whenever one or more objects are selected, all non-selected objects will be greyed out to highlight the selection.