[PD] why graph on parent ?

[joge .]

hi all .

i have been playing around recently with visual aspects of pd to aid in the
representation of some audio processing .  i stumbled upon the *graph on
parent* option when right clicking on a subpatch .   however , i dont see
the use of this option .  it doesnt seem like it is doing anything except
making a gray box which i can specify the dimensions of .  the graphical box
turn blue when i highlight it and then sometimes it turns black .
is there a way to get a certain a portion of a subpatch to graph on the
parent patch that is called from ?

joge .