Current process is as follows:
1. Invoked .exe gets the semaphore
2. Invoked .exe sets `InstanceProxy` values in running exe
3. Invoked .exe causes thread to spawn in running exe
4. New thread in running .exe reads values from `InstanceProxy`
4. Invoked .exe release the semaphore
The problem is that there is no guarantee on how fast new threads in
running .exe will spawn and read values from `InstanceProxy`. This PR
addresses that by moving the semaphore release from the invoked .exe to
the thread spawned in running .exe.
The problem is that multiple context menu selections spawn multiple .exe
(invoked). Each invoked .exe sets the InstanceProxy variables in the
running .exe and tells it to start a thread to process. But, there is no
waiting, so the InstanceProxy variables get clobbered before they can
get used.
This fix uses a semaphore to control the invoked .exe. There is only one
entry allowed forcing invoked .exe to wait until any other invoked .exe
is finished running and releases the semaphore.
