[Discuss-gnuradio] Change filter parameters in running flowgraph?

[John Ackermann N8UR]

I'm getting ready to do a Gnuradio tutorial for a local group, and want 
to show the impact of decimation and filtering.  I created a QT Gui 
Range parameter that sets the ID "decimation".

In the low pass filter block I the decimation value is set to 
"decimation."  That seems to work and I can see the span of the QT 
Frequency Sink change as the decimation value changes.

But I also use the decimation parameter to determine the cutoff 
frequency ((samp_rate/decimation)/2) and transition width 
((samp_rate/decimation)/10).  However, these don't seem to change 
dynamically when the flowgraph is running-- the filter remains at the 
width it was when the flowgraph started.

Is there a way to have the filter change as the decimation parameter 
changes?

Thanks,
John