merging group and view specific shader settings with the colour by annotation dialog

Jalview traditionally allows shading like:
A. per residue symbol (single colour, shade according to abundance in column, shade according to BLOSUM62 score against reference).
B. Thresholding of A according to PID abundance score or Bleaching according to Conservation Score computed for local group or alignment view.
C. Colour or thresholding according to values/colours in an annotation row (whole column or per sequence).

There are limitations:
Shading from A can be modified by B and then by C (if first A is applied, then B, then C - and the 'use original colours' selected)
Colours from C cannot be modified by B.
Groups can have individual settings for B - whilst this makes sense if a group spans a whole column, it makes less sense if groups are being compared down a column.
There is no group specific model for C.

It would be great if we could come up with a dialog which unifies the conservation, PID, and by annotation shading controls in a way that allows them to be used usefully together (e.g. visualise conservation in regions with highly conserved secondary structure with subfamilies across all families in an alignment)