If you disconnect a device, RSmapper cannot communicate with it anymore no matter how it was connected (BlueTooth or cable) Even if RSmapper would stay's running there is no way to use the disconnected device anymore. Look into a solution that will keep your BlueTooth up and running, this will keep RSmapper running too. Disconnecting a device cannot be solved by RSmapper so in my view it is not a bug.
DONATIONS? No idea about that, the link in HELP->ABOUT does not work.