Modulating a high pass filter creates a DC offset

[geckojsc]

This was already posted in the bugs topic, but I figured I'd make a topic for here too because it's pretty important for me.
When you lower the cutoff of a highpass filter down to 0 while audio is playing though it, the signal becomes offset (even after the source has stopped playing), like this:



I know the problem can be rectified by placing a DC blocker after the filter, but when the sound is being distorted and processed afterwards, adding a DC Blocker can significantly affect the feel of the resulting sound.

Example file:
http://dl.dropbox.com/u/11403463/drop/s ... bug.sunvox

Hope it can be fixed in a future release... If it requires introducing another 'controller 99' style feature to preserve backwards compatibility, that's okay with me.