How about this? It may require more testing to eliminate things like String controls that contain the search text, but that's easy enough (depending on the application).
This is a smart implementation but I personally would feel a little concerned about creating a potentially large XML string to get such an information. The solution from the original poster had one big problem that it only really checked for the refnum to be ANY ActiveX refnum. It should have gone further to not only compare two elements from the typestring but in fact 23 (possibly even 27 but I'm not sure those additional 4 words provide any meaningful information).
Basically the ActiveX specific typestring description contains a 0x3110, 0x0, 0x4, <16 bytes for the ActiveX Class GUID>, 0x0, 0x1, <16 bytes for the Interface GUID>, and then some other stuff (usually 0x0, 0x1, 0x0, 0x0). It's quite possible that the constant numbers could change with different ActiveX refnums, but my own testing seemed to indicate that they stay the same for several different ActiveX refnums, and quite likely are really the same for the same ActiveX type. To be really right the higher significant byte of the 2nd value of the full typestring should be masked out, as it contains LabVIEW private flags about the control the wire comes from.