I was trying a small thing with MPxCommand. I am aware of the capability of command plug-in is very limited. It is just a small try to see how can I get all the vertex point MPoint in MPointArray. Please have a look at code below. In debug mode I was checking the value for MpointArray, but it is strange that when I am appending the value of pt to R_pt, it takes just the first value of pt and the the MPointArray does not change it's value at all.
Adds a new element to the end of the array. If the array cannot be expanded in size by 1 element, then the append will fail and the existing array will remain unchanged.