Question

How would I make sure to create only a single thread on pushbutton without being accidently double-clicked?

Answer 1

The following code should do it (Under win32) …

EnterCriticalSection( &critSec );
if ( ghThread != INVALID_HANDLE_VALUE )
{
    ghThread    = ::CreateThread( NULL, stackSize, (LPTHREAD_START_ROUTINE)ThreadEntry, NULL, 0, NULL );
}
LeaveCriticalSection( &critSec );

This does of course assume you initialise the ghThread HANDLE to INVALID_HANDLE_VALUE in advance.