The colour switching thing happens in FL Studio whenever a parameter is changing. If you select the dot in the graph and hold the mouse button down the flickering happens. Could just be a graphics card thing at my end though. Also the lines in the background of the graph flicker as well (between solid and transparent). Either way it's probably not something worth woring about, crashes etc. are way more important.
Doesn't stop it from sounding fantastic (which is does!)
I can't get any other lowpass to go as low as PLParEq, it's ruined all my other EQ/filters for me
Thanks again.
(and yeah, I couldn't give a shit about the GUI either, but some potential clients might)
