Allow multiple special values

[sizezero]

Several people have asked for multiple special values to be selectable at the same time. There are several aspects that make this difficult.

1. Changing the special dropdown control to multiple selection is not difficult but displaying multiple specials in the closed listbox is not possible.

2. Calculations will be difficult. The current design accounts for only a single special. Many of the specials are incompatible and a new design will have to take this into account.