[juliansader]

Originally Posted by amagalma

How did you come up with 0x09DCB as the Menu identifier (IDM_*)?

I'm not sure why your Spy++ is reporting all these other commands. Perhaps check that it only logs the "FX: Track something" window, not all system windows?

If you set Spy++ to show "Raw Message Parameters", it will also report the wParam and lParam that the script must use when posting the message.

Alternatively, anyone that doesn't have Visual Studio and Spy++ can use this script to check the WM_COMMAND in REAPER's IDE:

-- Change this to however you prefer to select the window
w = reaper.JS_Window_FromPoint(reaper.GetMousePosition()) --Find("FX: Track 1", true)

t = {}
function loop()
    pOK, pass, time, wLow, wHigh, lLow, lHigh = reaper.JS_WindowMessage_Peek(w, "WM_COMMAND")
    if time ~= prevTime then
        prevTime = time
        t[#t+1] = {time = time, wLow = wLow, wHigh = wHigh, lLow = lLow, lHigh = lHigh}
    end
    reaper.defer(loop)
end

reaper.atexit(reaper.JS_WindowMessage_ReleaseWindow(w))

if w then 
    title = reaper.JS_Window_GetTitle(w, "")
    reaper.JS_WindowMessage_ReleaseWindow(w)
    iOK = reaper.JS_WindowMessage_Intercept(w, "WM_COMMAND", true)
    loop() 
end

(I checked in Linux, Windows x64 and x32, and they all seem to use the same number for the menu command, so I think it is safe to use.)