viewRender/beforeViewRender trigger

Hi, in a project I'm currently working on, we need to know when the calendar is going to be rendered. To do this, I needed to add this trigger. Would it be possible to have this merged upstream?

In case you're wondering, I need this for the following:
http://yokohama.savanne.be/tmp/.github/redlines.png

It adds a new background table to the calendar, which shows lines that indicate whether or not the slot is free / busy.

These lines need to be cleared upon switching to a new week, which is why I need the trigger.