Because Workplace Shell objects are running under the Workplace process, they can be accessed by any thread belonging to that process. And, as such, may have methods invoked upon them from any of these threads. Some Workplace Shell methods require the thread in which they were invoked to have a PM message queue. Therefore, when writing your own threads, in your subclass' implementation, make sure to do the following, even if your thread does not need a message loop:

hab = WinInitialize(0);
if (hab)
{
  hmq = WinCreateMsqQueue(hab,0);
  if (hmq)
  {
    WinCancelShutdown(hmq, TRUE);
        .
        .
        .
  }
}

Note:

• Exception handling should be added to any user-defined threads, so that traps originating in that code do not end up hanging the Workplace process.

• Per thread and per process variables are accessible via DosGetInfoBlocks, which yields a TIB structure.

• Threads require a 4KB stack each.

• When calling DosSetPriority, do not use idle priority threads.

• DosExit on a thread does not free resources nor close files; DosExit on a process does.