There have been requests before for better Multiview support, but this is a small step in that direction:
REQUEST: When using Multiview, one window with the General tab and the other with the Pattern tab, clicking on a channel's Mute button in the General tab window changes the channel's mute status in the Pattern tab window. However, it doesn't work in reverse, neither by clicking the channel header, or using its contextual menu. Would like to see MPT update both to make Multiview more beneficial.
Although this was rather a bug report...
Please confirm that this has been implemented as wished in in OpenMPT 1.18.02.00 (http://forum.openmpt.org/index.php?topic=3951.0). You may close this thread yourself then (edit first post and set the status in the topic title to S=C).