Change Colour (All Groups) applies PID threshold but not Conservation

Behaviour of Change Colour with Apply to All Groups selected is inconsistent:
- PID threshold is applied to all groups along with the selected colour scheme
- Consensus slider value is not

For example,
- load uniref50.fa and colour by helix propensity
- create a subgroup and colour by turn propensity
- apply a PID threshold to the alignment colour scheme
- select Colour | Apply Colour to All Groups and change to Hydrophobicity
   -> both colour and PID threshold are also applied to the sub-group
Compare the same procedure but with By Conservation instead of PID:
   -> the Conservation threshold is not applied to the sub-group