We recently came back to external application code and realized that certain apps including com.hp.printercontrol and es.rcti.printerplus which @Fabienne35 mentioned above were not being correctly launched from Collect. As @Grzesiek2010 states, not all applications will be able to return a meaningful value to Collect but it should be possible to start any application.
We believe this is now fixed in v1.29. @awaafo_donald please try the beta with the application you need to launch and let us know how it goes.