Hi Nick,
What is happening here is you are mixing threads and processes. Processes can have 1 or more thread associated with them while threads are singular entities. Look at the following code:

#define PROCESS_SET_INFORMATION		0x200
#define IDLE_PRIORITY_CLASS		0x40
declare integer OpenProcess in kernel32 integer lnaccess, integer lninherit, integer inprocID
declare integer GetLastError in win32api
declare integer SetPriorityClass in kernel32 integer, integer
declare integer CloseHandle in kernel32 integer
local lnhproc
lnhproc = OpenProcess(PROCESS_SET_INFORMATION,0,lnprocID)
if lnhproc = 0 ;
   or SetPriorityClass(lnhproc,IDLE_PRIORITY_CLASS) = 0 then
   ? GetLastError()
endif
CloseHandle(lnhproc)

For SetPriorityClass to work, you must pass in a process handle, not a thread handle. You need to use the OpenProcess function and because you are going to be setting information about the process, pass in the PROCESS_SET_INFORMATION flag.

As discussed before, the process ID is returned in one of the parameters you pass to GetWindowThreadProcessID and this is what needs to be passed to OpenProcess.


>I am also confused with using GetThreadPriority and BITOR stuff...

In order to use GetThreadPriority, you need to have read access to the thread. The THREAD_SET_INFORMATION flag only gives you write access to it. Using BITOR adds both flags together so you get read and write access to it.

lnhthread = OpenThread(BITOR(THREAD_SET_INFORMATION,THREAD_QUERY_INFORMATION),0,lnthreadID)  && give me write acces to set information and read access so I can verify my writes (if you don't believe the return value ;-)

HTH.

*snip*