Resizing the Tray after hiding Icons

[RCMoonUnit 0]

I'm trying to hide icons and using the SysTray UDF. Problem is that after hiding icons, the tray is full of empty space and won't resize itself. I've checked all the posts I can find related to this but none address this particular problem.

So I've tried using SENDMESSAGE to tell the tray to update/resize as suggested in one post but I don't really know what to do with the LPARAM. Here's my code: (any help would be very much appreciated including another method if something else would work better)

#include "SysTray_UDF.au3"
#NoTrayIcon

Local Const $WM_SIZE       = 5
Local Const $SIZE_RESTORED = 0

;get the number of icons in the tray
$n = _SystrayIconCount() + 1
MsgBox(0,"Debug Info","Icon count = " & $n)

;get pids of all processes that have an icon in the tray
$iPids = _SysTrayIconPids()

;make each hidden
For $i = 0 To UBound($iPids)-1
   _SysTrayIconHide(_SysTrayIconIndex($iPids[$i],2),1)
Next

Local $trayHwnd = _FindTrayToolbarWindow(1)
If $trayHwnd = -1 Then Exit
DllCall("user32.dll", "int", "SendMessageW", "hwnd", $trayHwnd, "uint", $WM_SIZE, "wparam", $SIZE_RESTORED, "lparam", 0)

Sleep(10000)

;make each visible
For $i = 0 To UBound($iPids)-1
   _SysTrayIconHide(_SysTrayIconIndex($iPids[$i],2),0)
Next