'Editor Selection' Values in Custom Block conditions not able to be parameterized

When creating a custom block condition, for normal variables you can supply a parameter to be fed into the condition for the genetic algorithm to be optimized. For example, in the indicator below, we have the Fast Period, Slow Period and Shift which I have manually added. However, the Compared Price parameter does not allow a parameter to be passed to it, and so does not allow this part of signal to be optimized by the algorithm. I want the option for the program to choose the Compared Price (Close, Open, High, Low etc.). This is an integer in the original code, and so it should allow an integer parameter (or equivalent selection parameter) to be passed to it to be able to be optimized by the code, like all the other fields have.