Блокировка мыши по оси y

Option Explicit
 
Private Type POINTAPI
    x           As Long
    y           As Long
End Type
 
Private Type MSG
    hwnd        As Long
    message     As Long
    wParam      As Long
    lParam      As Long
    time        As Long
    pt          As POINTAPI
End Type
 
Private Type MSLLHOOKSTRUCT
    pt          As POINTAPI
    mouseData   As Long
    flags       As Long
    time        As Long
    dwExtraInfo As Long
End Type
 
Private Declare Function GetMessage Lib "user32" Alias "GetMessageW" (lpMsg As Any, ByVal hwnd As Long, ByVal wMsgFilterMin As Long, ByVal wMsgFilterMax As Long) As Long
Private Declare Function TranslateMessage Lib "user32" (lpMsg As Any) As Long
Private Declare Function DispatchMessage Lib "user32" Alias "DispatchMessageW" (lpMsg As Any) As Long
Private Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExW" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Private Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Integer, lParam As Any) As Long
Private Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
Private Declare Function RegisterHotKey Lib "user32" (ByVal hwnd As Long, ByVal id As Long, ByVal fsModifiers As Long, ByVal vk As Long) As Long
Private Declare Function UnregisterHotKey Lib "user32" (ByVal hwnd As Long, ByVal id As Long) As Long
Private Declare Function SetCursorPos Lib "user32" (ByVal x As Long, ByVal y As Long) As Long
 
Private Const WH_MOUSE_LL       As Long = &HE&
Private Const HC_ACTION         As Long = 0
Private Const WM_MOUSEMOVE      As Long = &H200
Private Const MOD_CONTROL       As Long = &H2
Private Const WM_HOTKEY         As Long = &H312
 
Dim hHookMouse  As Long
Dim flag        As Boolean  ' Флаг, отвечающий за ограничение движения по оси Y
Dim lastFixPos  As POINTAPI
 
' // Стартовая процедура
Public Sub Main()
    Dim curMsg  As MSG
    Dim ret     As Long
    
    ' Без обработки ошибок, сделаешь сам
    ' Установка хука на мышь
    hHookMouse = SetWindowsHookEx(WH_MOUSE_LL, AddressOf LowLevelMouseProc, App.hInstance, 0)
 
    ' Регистрация горячих клавиш
    RegisterHotKey 0, 1, MOD_CONTROL, vbKey1
    RegisterHotKey 0, 2, MOD_CONTROL, vbKey2
    
    ' Цикл обработки сообщений потока
    Do
        
        ret = GetMessage(curMsg, 0, 0, 0)
        
        If ret = -1 Then
        
            MsgBox "Error msg loop"
            Exit Do
            
        ElseIf ret Then
                       
            TranslateMessage curMsg
            DispatchMessage curMsg
            
            ' Обработка "горячих" клавиш
            If curMsg.message = WM_HOTKEY Then
                
                Select Case curMsg.wParam
                ' Ctrl+1
                Case 1
                
                    flag = Not flag
                    ' Получаем позицию курсора на момент сообщения
                    If flag Then lastFixPos = curMsg.pt
                    
                ' Ctrl+2
                Case 2
                    Exit Do
                End Select
 
            End If
            
        End If
        
    Loop While ret
    
    ' Отмена регистраций
    UnregisterHotKey 0, 1
    UnregisterHotKey 0, 2
    ' Снятие хука
    UnhookWindowsHookEx hHookMouse
    
End Sub
 
' // Процедура обработки событий мыши
Private Function LowLevelMouseProc(ByVal uCode As Long, ByVal wParam As Long, lParam As MSLLHOOKSTRUCT) As Long
    
    If uCode = HC_ACTION And wParam = WM_MOUSEMOVE And flag Then
        
        ' Устанавливаем позицию, оставляя координату Y на момент нажатия "горячей" клавиши
        SetCursorPos lParam.pt.x, lastFixPos.y
        ' Выходим без дальнейшей обработки
        LowLevelMouseProc = -1
        Exit Function
                
    End If
    
    LowLevelMouseProc = CallNextHookEx(hHookMouse, uCode, wParam, lParam)
    
End Function