how to func_detail

Ctrl+T.
Adds entity to brush.
Therefore, brush-based entity.
For example, covering a cube of 256x256x256 with tools/trigger and pressing Ctrl+T, would give you a selection of entities. Selecting trigger_hurt and changing the keyvalue of damage to 5000 would give 5000 damage to anyone who touches that cube.

There's also a button named 'ToEntity', does exact thing as Ctrl+T.
if you turned a solid brush to a entity brush by accident/mistake, you can always return it to solid by clicking the 'ToEntity'-button's neighbour: 'ToWorld'.