[plt-scheme] on-resize in pasteboard%

I am trying to derive a class from pasteboard% that will need to be alerted
when snips inside of it are resized. on-resize is called when snips are
resized by the pasteboard itself (i.e. (send pasteboard resize snip)) but
i need to know when the snips are resize at other times, for instants when
an editor snip's text gets a newline, the size will often change to get bigger.

is there a way to monitor size changes of a pasteboard's snips?

-mike