### 2.2.53 Grob_pq_engraver

Administrate when certain grobs (e.g., note heads) stop playing.

Properties (read)

> `busyGrobs` (list)

>   A queue of `(end-moment . grob)` cons cells. This is for internal (C++) use only. This property contains the grobs which are still busy (e.g. note heads, spanners, etc.).

Properties (write)

> `busyGrobs` (list)

>   A queue of `(end-moment . grob)` cons cells. This is for internal (C++) use only. This property contains the grobs which are still busy (e.g. note heads, spanners, etc.).

`Grob_pq_engraver` is part of the following context(s): CueVoice, DrumStaff, DrumVoice, GregorianTranscriptionStaff, GregorianTranscriptionVoice, KievanStaff, KievanVoice, MensuralStaff, MensuralVoice, PetrucciStaff, PetrucciVoice, Staff, TabStaff, TabVoice, VaticanaStaff, VaticanaVoice and Voice.

#### Internals Reference v2.18.2 (稳定分支).