It would be nice to consider a double click on a control (Mixer slider, Knob) to make it return to its suggested defaults. As an example by double licking on a mixer slider it could be returned to 0db or by doing the same on Glide, Strike, Pressure, CC74 turned to 50,50,50,0 or what the magic JamOrigin suggests to. The mapped controls of a VST/AU Synth should not exhibit this behavior unless the system (MG3) can set aside the value of the Synth Patch after the first mapping to treat that as the deafult but I think it might get complicated as different behavior in the same GUI.
Hope this helps
Pasha