GUIGetMsg() and Dragging a TITLE BAR to the top

[argumentum]

In Win10, you can drag the TITLE BAR to the top of the monitor and the GUI will maximize. GUIGetMsg() does not trigger the event.
I believe to understand why, but maybe there can be a fix for the unexpected behavior in GUIGetMsg() not triggering the event.

Here is a sampler to show expected behavior via WM_WINDOWPOSCHANGING > _WinAPI_GetWindowPlacement()

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#include <AutoItConstants.au3>
#include <GUIConstants.au3>
#include <WinAPIMisc.au3>
#include <WinAPIGdi.au3>
#include <WinAPISysWin.au3> ; _WinAPI_GetWindowPlacement
#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <SendMessage.au3>

Global Const $SC_DRAGMOVE = 0xF012

Global $__g_WINDOWPOSCHANGING_iGap = 10 ; 30 pixels for "dramatic effect", 10 pixels should be good for the "magnetic pull"
Global $__g_WINDOWPOSCHANGING_iEdge = BitOR(1, 2, 4, 8) ; = 15 ; Left, Top, Right, Bottom
Global $__g_WINDOWPOSCHANGING_aBorderWidth[4] = [0, 0, 0, 0] ; Left, Top, Right, Bottom ; for _SetGETMINMAXINFOBorderWidth()
Global $__g_aGETMINMAXINFO[4] = [0,0,0,0] ; for WM_GETMINMAXINFO() to limit GUI minimum and/or maximum size. Default of zero means disable.
Global $idBtnStyle, $iTest_GUIGetMsg_ON = 1 ; <<<< set to zero to show the expected behaviour

Example()
Func Example()
    Local $hGUI = GUICreate("Snapped Window multi-monitor", 500, 300)
    _SetGETMINMAXINFO(300, 200, 800)
    ConsoleWrite('@OSVersion = ' & @OSVersion & @CRLF)
    If @OSVersion <> "WIN_10" Then _SetGETMINMAXINFOBorderWidth("OFF")
    GUISetBkColor(0x505254)
    Local $bNewStyle = True ; False
    $idBtnStyle = GUICtrlCreateButton("Undo Style", 5, 50, 200, 25)
    GUIRegisterMsg($WM_WINDOWPOSCHANGING, "WM_WINDOWPOSCHANGING")
    GUIRegisterMsg($WM_GETMINMAXINFO, "WM_GETMINMAXINFO")
    GUISetStyle(BitOR($GUI_SS_DEFAULT_GUI, $WS_MAXIMIZEBOX, $WS_SIZEBOX, $WS_THICKFRAME, $WS_TABSTOP))
    _GUIStyleRefresh($hGUI)
    _SetGETMINMAXINFOBorderWidth($hGUI)
    _GuiCenterOnMonitorFromMousePosition($hGUI)
    GUISetState()

    While 1
        Switch GUIGetMsg()
            Case $GUI_EVENT_CLOSE
                GUIDelete()
                ExitLoop

             Case $GUI_EVENT_PRIMARYDOWN
                _SendMessage($hGUI, $WM_SYSCOMMAND, $SC_DRAGMOVE, 0)

;               Moved to WM_WINDOWPOSCHANGING() for this example. GUIGetMsg() does not act on size events when the TITLE bar is dragged.
            Case $GUI_EVENT_MAXIMIZE, $GUI_EVENT_RESTORE ; should not change to this style while maximized
                If $iTest_GUIGetMsg_ON Then GUICtrlSetState($idBtnStyle, (BitAND(WinGetState($hGUI), $WIN_STATE_MAXIMIZED) ? $GUI_DISABLE : $GUI_ENABLE))

            Case $idBtnStyle
                $bNewStyle = Not $bNewStyle
                If $bNewStyle Then
                    GUISetStyle(BitOR($GUI_SS_DEFAULT_GUI, $WS_MAXIMIZEBOX, $WS_SIZEBOX, $WS_THICKFRAME, $WS_TABSTOP))
                Else
                    GUISetStyle($GUI_SS_DEFAULT_GUI)
;~                  GUISetStyle($WS_POPUP)
                EndIf
                GUICtrlSetData($idBtnStyle, ($bNewStyle ? 'Undo Style' : 'Change Style'))
                _GUIStyleRefresh($hGUI)
                _SetGETMINMAXINFOBorderWidth($hGUI)
                _GUIStyleRefresh($hGUI) ; ..with new SetGETMINMAXINFOBorderWidth


        EndSwitch
    WEnd
EndFunc   ;==>Example

Func _SetGETMINMAXINFO($iMinTrackSizeX = Default, $iMinTrackSizeY = Default, $iMaxTrackSizeX = Default, $iMaxTrackSizeY = Default)
;~  $tagMINMAXINFO = 'struct; long ReservedX;long ReservedY;long MaxSizeX;long MaxSizeY;long MaxPositionX;long MaxPositionY;long MinTrackSizeX;long MinTrackSizeY;long MaxTrackSizeX;long MaxTrackSizeY; endstruct'
    If $iMinTrackSizeX <> Default Then $__g_aGETMINMAXINFO[0] = $iMinTrackSizeX ; https://www.autoitscript.com/forum/topic/144385-restricting-the-minimum-and-maximum-sizes-of-a-gui/
    If $iMinTrackSizeY <> Default Then $__g_aGETMINMAXINFO[1] = $iMinTrackSizeY
    If $iMaxTrackSizeX <> Default Then $__g_aGETMINMAXINFO[2] = $iMaxTrackSizeX
    If $iMaxTrackSizeY <> Default Then $__g_aGETMINMAXINFO[3] = $iMaxTrackSizeY
    Return $__g_aGETMINMAXINFO
EndFunc

Func WM_GETMINMAXINFO($hWnd, $msg, $wParam, $lParam)
    Local $tagMINMAXINFO = DllStructCreate("struct;long;long;long;long;long;long;long MinTrackSizeX;long MinTrackSizeY;long MaxTrackSizeX;long MaxTrackSizeY;endstruct", $lParam)
    If $__g_aGETMINMAXINFO[0] Then $tagMINMAXINFO.MinTrackSizeX = $__g_aGETMINMAXINFO[0] ; DllStructSetData($tagMINMAXINFO, 7, $__g_aGETMINMAXINFO[0]) ; min X
    If $__g_aGETMINMAXINFO[1] Then $tagMINMAXINFO.MinTrackSizeY = $__g_aGETMINMAXINFO[1]
    If $__g_aGETMINMAXINFO[2] Then $tagMINMAXINFO.MaxTrackSizeX = $__g_aGETMINMAXINFO[2]
    If $__g_aGETMINMAXINFO[3] Then $tagMINMAXINFO.MaxTrackSizeY = $__g_aGETMINMAXINFO[3]
    Return $GUI_RUNDEFMSG
EndFunc   ;==>WM_GETMINMAXINFO

Func _SetGETMINMAXINFOBorderWidth($hWnd, $iLeft = Default, $iTop = Default, $iRight = Default, $iBottom = Default )
    Local Static $iAutoBorderWidthEnabled = 1
    Switch $hWnd
        Case "ON"
            $iAutoBorderWidthEnabled = 1
            Return SetError(0, $iAutoBorderWidthEnabled, $__g_WINDOWPOSCHANGING_aBorderWidth)
        Case "OFF"
            $iAutoBorderWidthEnabled = 0
            Return SetError(0, $iAutoBorderWidthEnabled, $__g_WINDOWPOSCHANGING_aBorderWidth)
        Case "SET"
            If $iLeft <> Default Then $__g_WINDOWPOSCHANGING_aBorderWidth[0] = $iLeft
            If $iTop <> Default Then $__g_WINDOWPOSCHANGING_aBorderWidth[1] = $iTop
            If $iRight <> Default Then $__g_WINDOWPOSCHANGING_aBorderWidth[2] = $iRight
            If $iBottom <> Default Then $__g_WINDOWPOSCHANGING_aBorderWidth[3] = $iBottom
            Return SetError(0, $iAutoBorderWidthEnabled, $__g_WINDOWPOSCHANGING_aBorderWidth)
        Case "RESET"
            $__g_WINDOWPOSCHANGING_aBorderWidth[0] = 0
            $__g_WINDOWPOSCHANGING_aBorderWidth[1] = 0
            $__g_WINDOWPOSCHANGING_aBorderWidth[2] = 0
            $__g_WINDOWPOSCHANGING_aBorderWidth[3] = 0
            Return SetError(0, $iAutoBorderWidthEnabled, $__g_WINDOWPOSCHANGING_aBorderWidth)
    EndSwitch
    If Not $iAutoBorderWidthEnabled Then Return
    Local $aWinPos = WinGetPos($hWnd)
    Local $aWinClientSize = WinGetClientSize($hWnd)
    Local $iBorder = (($aWinPos[2] - $aWinClientSize[0]) / 2)
    Local $iHeader = $aWinPos[3] - $aWinClientSize[1] - $iBorder
    ConsoleWrite( '>>> ' & $iBorder & @TAB & $iHeader & @CRLF)
    If $iBorder Then $iBorder -= 1 ; auto-adjusting for Windows 10 border ; -1 or will otherwise show part in the adjacent monitor in multi-monitor setup.
    $__g_WINDOWPOSCHANGING_aBorderWidth[0] = - $iBorder
    $__g_WINDOWPOSCHANGING_aBorderWidth[2] = $iBorder
    $__g_WINDOWPOSCHANGING_aBorderWidth[3] = $iBorder
    Return SetError(0, $iAutoBorderWidthEnabled, $__g_WINDOWPOSCHANGING_aBorderWidth)
EndFunc

Func _GUIStyleRefresh($hWnd)
    Local $aWinPos = WinGetPos($hWnd)
    If @error Then Return SetError(@error, @extended, @error)
    WinMove($hWnd, "", $aWinPos[0], $aWinPos[1], $aWinPos[2] - 1, $aWinPos[3] - 1)
    WinMove($hWnd, "", $aWinPos[0], $aWinPos[1], $aWinPos[2], $aWinPos[3])
    Return
EndFunc   ;==>GUIStyleRefresh

Func WM_WINDOWPOSCHANGING($hWnd, $iMsg, $wParam, $lParam)
    #forceref $hWnd, $iMsg, $wParam
    ; original code at https://www.autoitscript.com/forum/topic/24342-form-snap/
;~  ConsoleWrite('+ WM_WINDOWPOSCHANGING(' & $hWnd & ', ' & $iMsg & ', ' & $wParam & ', ' & $lParam & ') ' & @SEC &'.'& @MSEC & @CRLF)

    ; The Static declaration speeds up the func. ( not much, nanoseconds )
    Local Static $stWinPos, $tPos, $hMonitor, $aData, $nLeft, $nTop, $nRight, $nBottom, $iShowCmd = 0, $hTimer = 0

    If TimerDiff($hTimer) > 1000 Then
        $hTimer = TimerInit()
        $tPos = _WinAPI_GetMousePos()                                  ;  These func are very time consuming and
        If Not @error Then $hMonitor = _WinAPI_MonitorFromPoint($tPos) ;  the user is very unlikely to move the
        If Not @error Then $aData = _WinAPI_GetMonitorInfo($hMonitor)  ;  mouse into position on another monitor
        If @error Then Return $GUI_RUNDEFMSG                           ;  in less than a second.
    EndIf

    ; https://docs.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-windowpos?redirectedfrom=MSDN
    $stWinPos = DllStructCreate("hwnd hwnd;hwnd hwndInsertAfter;int x;int y;int cx;int cy;uint flags", $lParam) ; $tagWINDOWPOS
    $nLeft = $aData[1].Left
    $nTop = $aData[1].Top     ; $tagRECT = "struct;long Left;long Top;long Right;long Bottom;endstruct"
    $nRight = $aData[1].Right - $stWinPos.cx
    $nBottom = $aData[1].Bottom - $stWinPos.cy

    If BitAND($stWinPos.flags, 0x0020) Then ; SWP_FRAMECHANGED ; https://docs.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-windowpos
        Local $tRET = _WinAPI_GetWindowPlacement($hWnd)
        If @error = 0 Then ; https://docs.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-windowplacement
            $iShowCmd = $tRET.showCmd ; $tagWINDOWPLACEMENT = "uint length;uint flags;uint showCmd;long ptMinPosition[2];long ptMaxPosition[2];long rcNormalPosition[4]"

            Local Static $aShowCmd[10] = ["SW_HIDE","SW_SHOWNORMAL","SW_SHOWMINIMIZED","SW_MAXIMIZE","SW_SHOWNOACTIVATE","SW_SHOW","SW_MINIMIZE","SW_SHOWMINNOACTIVE","SW_SHOWNA","SW_RESTORE"]
            ConsoleWrite($aShowCmd[$iShowCmd] & @CRLF) ; ..just for show

            ; dragging the title will change state and GUIGetMsg() will not act on it, so is better running here.
            If $iTest_GUIGetMsg_ON = 0 Then GUICtrlSetState($idBtnStyle, $iShowCmd = @SW_MAXIMIZE ? $GUI_DISABLE : $GUI_ENABLE)
        EndIf
    EndIf

    If $iShowCmd = @SW_MAXIMIZE Then Return $GUI_RUNDEFMSG

    If BitAND($__g_WINDOWPOSCHANGING_iEdge, 1) And Abs($nLeft - $stWinPos.x) <= $__g_WINDOWPOSCHANGING_iGap Then $stWinPos.x = $nLeft + $__g_WINDOWPOSCHANGING_aBorderWidth[0]
    If BitAND($__g_WINDOWPOSCHANGING_iEdge, 4) And Abs($nRight - $stWinPos.x) <= $__g_WINDOWPOSCHANGING_iGap Then $stWinPos.x = $nRight + $__g_WINDOWPOSCHANGING_aBorderWidth[2]
    If BitAND($__g_WINDOWPOSCHANGING_iEdge, 8) And Abs($nBottom - $stWinPos.y) <= $__g_WINDOWPOSCHANGING_iGap Then $stWinPos.y = $nBottom + $__g_WINDOWPOSCHANGING_aBorderWidth[3]
    If BitAND($__g_WINDOWPOSCHANGING_iEdge, 2) And Abs($nTop - $stWinPos.y) <= $__g_WINDOWPOSCHANGING_iGap Then $stWinPos.y = $nTop + $__g_WINDOWPOSCHANGING_aBorderWidth[1]

    Return $GUI_RUNDEFMSG
EndFunc   ;==>WM_WINDOWPOSCHANGING

Func _GuiCenterOnMonitorFromMousePosition($hForm, $sText = "")
    ; https://www.autoitscript.com/forum/index.php?showtopic=139260&view=findpost&p=1479329
    Local $aData, $hMonitor, $tPos = _WinAPI_GetMousePos()
    If Not @error Then $hMonitor = _WinAPI_MonitorFromPoint($tPos)
    If Not @error Then $aData = _WinAPI_GetMonitorInfo($hMonitor)
    If @error Then Return SetError(1, -1, 1)
    Local $iWinState = WinGetState($hForm, $sText)
    If @error Then Return SetError(2, $aData[2], 2)
    If BitAND($iWinState, $WIN_STATE_MINIMIZED) Or _
            BitAND($iWinState, $WIN_STATE_MAXIMIZED) Then WinSetState($hForm, $sText, @SW_RESTORE)
    Local $aWinPos = WinGetPos($hForm, $sText)
    If @error Then Return SetError(3, $aData[2], 3)
    WinMove($hForm, _
            $sText, _
            Int((($aData[0].Right - $aData[0].Left - $aWinPos[2]) / 2) + $aData[0].Left), _
            Int((($aData[0].Bottom - $aData[0].Top - $aWinPos[3]) / 2) + $aData[0].Top))
    If @error Then Return SetError(4, $aData[2], 4)
    If BitAND($iWinState, $WIN_STATE_MINIMIZED) Then WinSetState($hForm, $sText, @SW_MINIMIZE)
    If BitAND($iWinState, $WIN_STATE_MAXIMIZED) Then WinSetState($hForm, $sText, @SW_MAXIMIZE)
    Return SetError(0, $aData[2], 0)
EndFunc   ;==>GuiCenterOnMonitorFromMousePosition

...well, a sampler that is like a "example type of script" but I did not know where to post it to ask if it deserves opening a ticket or not. Tho it should.
@jpm, will you give your 2 cents  

Edit: $GUI_EVENT_RESIZED does trigger ( OnEvent or not ).
  Maybe the patch can be around there in the source ?, no clue.

Edited April 8, 2021 by argumentum