Imports System.Runtime.InteropServices
 
Public Class Form1
    Implements IMessageFilter
 
    ' Noch nicht rekursiv!
    Private Function FindWindowFromHandle(ByVal hWnd As IntPtr) As Control
        If hWnd = Me.Handle Then Return Me
        For Each c As Control In Controls
            If hWnd = c.Handle Then Return c
        Next
        Return Nothing
    End Function
 
    Dim controlWithMouse As Control
    Dim mouseInClient As Boolean
 
    Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) _
      As Boolean Implements System.Windows.Forms.IMessageFilter.PreFilterMessage
 
        Select Case m.Msg
            Case WM_MOUSEMOVE
                If Not mouseInClient Then
                    controlWithMouse = FindWindowFromHandle(m.HWnd)
                    If controlWithMouse Is Nothing Then
                        Debug.WriteLine("Enterered unknown")
                        Return False
                    Else
                        Debug.WriteLine("Entered " & controlWithMouse.Name)
                    End If
                    mouseInClient = True
                End If
            Case WM_MOUSELEAVE
                mouseInClient = False
                If controlWithMouse Is Nothing Then
                    Debug.WriteLine("Left unknown")
                    Return False
                Else
                    Debug.WriteLine("Left " & controlWithMouse.Name)
                    controlWithMouse = Nothing
                End If
        End Select
        Return False
    End Function
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Application.AddMessageFilter(Me)
    End Sub
End Class

Module WinDefs
 
 
    Public Const WM_NULL As Integer = &H0
    Public Const WM_CREATE As Integer = &H1
    Public Const WM_DESTROY As Integer = &H2
    Public Const WM_MOVE As Integer = &H3
    Public Const WM_SIZE As Integer = &H5
 
    Public Const WM_ACTIVATE As Integer = &H6
 
    '
    ' WM_ACTIVATE state values
 
    Public Const WA_INACTIVE As Integer = 0
    Public Const WA_ACTIVE As Integer = 1
    Public Const WA_CLICKACTIVE As Integer = 2
 
    Public Const WM_SETFOCUS As Integer = &H7
    Public Const WM_KILLFOCUS As Integer = &H8
    Public Const WM_ENABLE As Integer = &HA
    Public Const WM_SETREDRAW As Integer = &HB
    Public Const WM_SETTEXT As Integer = &HC
    Public Const WM_GETTEXT As Integer = &HD
    Public Const WM_GETTEXTLENGTH As Integer = &HE
    Public Const WM_PAINT As Integer = &HF
    Public Const WM_CLOSE As Integer = &H10
    Public Const WM_QUERYENDSESSION As Integer = &H11
    Public Const WM_QUIT As Integer = &H12
    Public Const WM_QUERYOPEN As Integer = &H13
    Public Const WM_ERASEBKGND As Integer = &H14
    Public Const WM_SYSCOLORCHANGE As Integer = &H15
    Public Const WM_ENDSESSION As Integer = &H16
    Public Const WM_SHOWWINDOW As Integer = &H18
    Public Const WM_WININICHANGE As Integer = &H1A
 
    Public Const WM_SETTINGCHANGE As Integer = WM_WININICHANGE
 
    Public Const WM_DEVMODECHANGE As Integer = &H1B
    Public Const WM_ACTIVATEAPP As Integer = &H1C
    Public Const WM_FONTCHANGE As Integer = &H1D
    Public Const WM_TIMECHANGE As Integer = &H1E
    Public Const WM_CANCELMODE As Integer = &H1F
    Public Const WM_SETCURSOR As Integer = &H20
    Public Const WM_MOUSEACTIVATE As Integer = &H21
    Public Const WM_CHILDACTIVATE As Integer = &H22
    Public Const WM_QUEUESYNC As Integer = &H23
 
    Public Const WM_GETMINMAXINFO As Integer = &H24
 
    ' Struct pointed to by WM_GETMINMAXINFO lParam
 
    'public type MINMAXINFO {
    '    POINT ptReserved
    '    POINT ptMaxSize
    '    POINT ptMaxPosition
    '    POINT ptMinTrackSize
    '    POINT ptMaxTrackSize
    'End Type
 
    Public Const WM_PAINTICON As Integer = &H26
    Public Const WM_ICONERASEBKGND As Integer = &H27
    Public Const WM_NEXTDLGCTL As Integer = &H28
    Public Const WM_SPOOLERSTATUS As Integer = &H2A
    Public Const WM_DRAWITEM As Integer = &H2B
    Public Const WM_MEASUREITEM As Integer = &H2C
    Public Const WM_DELETEITEM As Integer = &H2D
    Public Const WM_VKEYTOITEM As Integer = &H2E
    Public Const WM_CHARTOITEM As Integer = &H2F
    Public Const WM_SETFONT As Integer = &H30
    Public Const WM_GETFONT As Integer = &H31
    Public Const WM_SETHOTKEY As Integer = &H32
    Public Const WM_GETHOTKEY As Integer = &H33
    Public Const WM_QUERYDRAGICON As Integer = &H37
    Public Const WM_COMPAREITEM As Integer = &H39
 
    Public Const WM_GETOBJECT As Integer = &H3D
 
    Public Const WM_COMPACTING As Integer = &H41
    Public Const WM_COMMNOTIFY As Integer = &H44   ' no Integerer suported
    Public Const WM_WINDOWPOSCHANGING As Integer = &H46
    Public Const WM_WINDOWPOSCHANGED As Integer = &H47
 
    Public Const WM_POWER As Integer = &H48
    '
    ' wParam for WM_POWER window message and DRV_POWER driver notification
    '
    Public Const PWR_OK As Integer = 1
    Public Const PWR_FAIL As Integer = (-1)
    Public Const PWR_SUSPENDREQUEST As Integer = 1
    Public Const PWR_SUSPENDRESUME As Integer = 2
    Public Const PWR_CRITICALRESUME As Integer = 3
 
    Public Const WM_COPYDATA As Integer = &H4A
    Public Const WM_CANCELJOURNAL As Integer = &H4B
 
    '
    ' lParam of WM_COPYDATA message points to...
    '
    'public Type COPYDATASTRUCT
    '    DWORD dwData
    '    DWORD cbData
    '    PVOID lpData
    'End Type
 
    Public Const WM_NOTIFY As Integer = &H4E
    Public Const WM_INPUTLANGCHANGEREQUEST As Integer = &H50
    Public Const WM_INPUTLANGCHANGE As Integer = &H51
    Public Const WM_TCARD As Integer = &H52
    Public Const WM_HELP As Integer = &H53
    Public Const WM_USERCHANGED As Integer = &H54
    Public Const WM_NOTIFYFORMAT As Integer = &H55
 
    Public Const NFR_ANSI As Integer = 1
    Public Const NFR_UNICODE As Integer = 2
    Public Const NF_QUERY As Integer = 3
    Public Const NF_REQUERY As Integer = 4
 
    Public Const WM_CONTEXTMENU As Integer = &H7B
    Public Const WM_STYLECHANGING As Integer = &H7C
    Public Const WM_STYLECHANGED As Integer = &H7D
    Public Const WM_DISPLAYCHANGE As Integer = &H7E
    Public Const WM_GETICON As Integer = &H7F
    Public Const WM_SETICON As Integer = &H80
 
    Public Const WM_NCCREATE As Integer = &H81
    Public Const WM_NCDESTROY As Integer = &H82
    Public Const WM_NCCALCSIZE As Integer = &H83
    Public Const WM_NCHITTEST As Integer = &H84
    Public Const WM_NCPAINT As Integer = &H85
    Public Const WM_NCACTIVATE As Integer = &H86
    Public Const WM_GETDLGCODE As Integer = &H87
    Public Const WM_SYNCPAINT As Integer = &H88
    Public Const WM_NCMOUSEMOVE As Integer = &HA0
    Public Const WM_NCLBUTTONDOWN As Integer = &HA1
    Public Const WM_NCLBUTTONUP As Integer = &HA2
    Public Const WM_NCLBUTTONDBLCLK As Integer = &HA3
    Public Const WM_NCRBUTTONDOWN As Integer = &HA4
    Public Const WM_NCRBUTTONUP As Integer = &HA5
    Public Const WM_NCRBUTTONDBLCLK As Integer = &HA6
    Public Const WM_NCMBUTTONDOWN As Integer = &HA7
    Public Const WM_NCMBUTTONUP As Integer = &HA8
    Public Const WM_NCMBUTTONDBLCLK As Integer = &HA9
 
    Public Const WM_KEYFIRST As Integer = &H100
    Public Const WM_KEYDOWN As Integer = &H100
    Public Const WM_KEYUP As Integer = &H101
    Public Const WM_CHAR As Integer = &H102
    Public Const WM_DEADCHAR As Integer = &H103
    Public Const WM_SYSKEYDOWN As Integer = &H104
    Public Const WM_SYSKEYUP As Integer = &H105
    Public Const WM_SYSCHAR As Integer = &H106
    Public Const WM_SYSDEADCHAR As Integer = &H107
    Public Const WM_KEYLAST As Integer = &H108
 
    Public Const WM_IME_STARTCOMPOSITION As Integer = &H10D
    Public Const WM_IME_ENDCOMPOSITION As Integer = &H10E
    Public Const WM_IME_COMPOSITION As Integer = &H10F
    Public Const WM_IME_KEYLAST As Integer = &H10F
 
    Public Const WM_INITDIALOG As Integer = &H110
    Public Const WM_COMMAND As Integer = &H111
    Public Const WM_SYSCOMMAND As Integer = &H112
    Public Const WM_TIMER As Integer = &H113
    Public Const WM_HSCROLL As Integer = &H114
    Public Const WM_VSCROLL As Integer = &H115
    Public Const WM_INITMENU As Integer = &H116
    Public Const WM_INITMENUPOPUP As Integer = &H117
    Public Const WM_MENUSELECT As Integer = &H11F
    Public Const WM_MENUCHAR As Integer = &H120
    Public Const WM_ENTERIDLE As Integer = &H121
 
    Public Const WM_MENURBUTTONUP As Integer = &H122
    Public Const WM_MENUDRAG As Integer = &H123
    Public Const WM_MENUGETOBJECT As Integer = &H124
    Public Const WM_UNINITMENUPOPUP As Integer = &H125
    Public Const WM_MENUCOMMAND As Integer = &H126
 
    Public Const WM_CTLCOLORMSGBOX As Integer = &H132
    Public Const WM_CTLCOLOREDIT As Integer = &H133
    Public Const WM_CTLCOLORLISTBOX As Integer = &H134
    Public Const WM_CTLCOLORBTN As Integer = &H135
    Public Const WM_CTLCOLORDLG As Integer = &H136
    Public Const WM_CTLCOLORSCROLLBAR As Integer = &H137
    Public Const WM_CTLCOLORSTATIC As Integer = &H138
 
 
    Public Const WM_MOUSEFIRST As Integer = &H200
    Public Const WM_MOUSEMOVE As Integer = &H200
    Public Const WM_LBUTTONDOWN As Integer = &H201
    Public Const WM_LBUTTONUP As Integer = &H202
    Public Const WM_LBUTTONDBLCLK As Integer = &H203
    Public Const WM_RBUTTONDOWN As Integer = &H204
    Public Const WM_RBUTTONUP As Integer = &H205
    Public Const WM_RBUTTONDBLCLK As Integer = &H206
    Public Const WM_MBUTTONDOWN As Integer = &H207
    Public Const WM_MBUTTONUP As Integer = &H208
    Public Const WM_MBUTTONDBLCLK As Integer = &H209
 
    Public Const WM_MOUSEWHEEL As Integer = &H20A
    Public Const WM_MOUSELAST As Integer = &H20A
 
    'public Const WM_MOUSELAST          As Integer = &H209
 
    Public Const WHEEL_DELTA As Integer = 120                        ' Value 
    ' for rolling one detent '
 
    'public Const WHEEL_PAGESCROLL As Integer = (UINT_MAX)     ' Scroll one page
 
    Public Const WM_PARENTNOTIFY As Integer = &H210
    Public Const WM_ENTERMENULOOP As Integer = &H211
    Public Const WM_EXITMENULOOP As Integer = &H212
 
    Public Const WM_NEXTMENU As Integer = &H213
 
    'public Type MDINEXTMENU
    'HMENU   hmenuIn
    'HMENU   hmenuNext
    'HWND    hwndNext
    'End Type
 
    Public Const WM_SIZING As Integer = &H214
    Public Const WM_CAPTURECHANGED As Integer = &H215
    Public Const WM_MOVING As Integer = &H216
 
    Public Const WM_POWERBROADCAST As Integer = &H218
 
    Public Const PBT_APMQUERYSUSPEND As Integer = &H0
    Public Const PBT_APMQUERYSTANDBY As Integer = &H1
 
    Public Const PBT_APMQUERYSUSPENDFAILED As Integer = &H2
    Public Const PBT_APMQUERYSTANDBYFAILED As Integer = &H3
 
    Public Const PBT_APMSUSPEND As Integer = &H4
    Public Const PBT_APMSTANDBY As Integer = &H5
 
    Public Const PBT_APMRESUMECRITICAL As Integer = &H6
    Public Const PBT_APMRESUMESUSPEND As Integer = &H7
    Public Const PBT_APMRESUMESTANDBY As Integer = &H8
 
    Public Const PBTF_APMRESUMEFROMFAILURE As Integer = &H1
 
    Public Const PBT_APMBATTERYLOW As Integer = &H9
    Public Const PBT_APMPOWERSTATUSCHANGE As Integer = &HA
 
    Public Const PBT_APMOEMEVENT As Integer = &HB
    Public Const PBT_APMRESUMEAUTOMATIC As Integer = &H12
    Public Const WM_DEVICECHANGE As Integer = &H219
 
    Public Const WM_MDICREATE As Integer = &H220
    Public Const WM_MDIDESTROY As Integer = &H221
    Public Const WM_MDIACTIVATE As Integer = &H222
    Public Const WM_MDIRESTORE As Integer = &H223
    Public Const WM_MDINEXT As Integer = &H224
    Public Const WM_MDIMAXIMIZE As Integer = &H225
    Public Const WM_MDITILE As Integer = &H226
    Public Const WM_MDICASCADE As Integer = &H227
    Public Const WM_MDIICONARRANGE As Integer = &H228
    Public Const WM_MDIGETACTIVE As Integer = &H229
 
    Public Const WM_MDISETMENU As Integer = &H230
    Public Const WM_ENTERSIZEMOVE As Integer = &H231
    Public Const WM_EXITSIZEMOVE As Integer = &H232
    Public Const WM_DROPFILES As Integer = &H233
    Public Const WM_MDIREFRESHMENU As Integer = &H234
 
    Public Const WM_IME_SETCONTEXT As Integer = &H281
    Public Const WM_IME_NOTIFY As Integer = &H282
    Public Const WM_IME_CONTROL As Integer = &H283
    Public Const WM_IME_COMPOSITIONFULL As Integer = &H284
    Public Const WM_IME_SELECT As Integer = &H285
    Public Const WM_IME_CHAR As Integer = &H286
 
    Public Const WM_IME_REQUEST As Integer = &H288
 
    Public Const WM_IME_KEYDOWN As Integer = &H290
    Public Const WM_IME_KEYUP As Integer = &H291
 
    Public Const WM_MOUSEHOVER As Integer = &H2A1
    Public Const WM_MOUSELEAVE As Integer = &H2A3
 
    Public Const WM_CUT As Integer = &H300
    Public Const WM_COPY As Integer = &H301
    Public Const WM_PASTE As Integer = &H302
    Public Const WM_CLEAR As Integer = &H303
    Public Const WM_UNDO As Integer = &H304
    Public Const WM_RENDERFORMAT As Integer = &H305
    Public Const WM_RENDERALLFORMATS As Integer = &H306
    Public Const WM_DESTROYCLIPBOARD As Integer = &H307
    Public Const WM_DRAWCLIPBOARD As Integer = &H308
    Public Const WM_PAINTCLIPBOARD As Integer = &H309
    Public Const WM_VSCROLLCLIPBOARD As Integer = &H30A
    Public Const WM_SIZECLIPBOARD As Integer = &H30B
    Public Const WM_ASKCBFORMATNAME As Integer = &H30C
    Public Const WM_CHANGECBCHAIN As Integer = &H30D
    Public Const WM_HSCROLLCLIPBOARD As Integer = &H30E
    Public Const WM_QUERYNEWPALETTE As Integer = &H30F
    Public Const WM_PALETTEISCHANGING As Integer = &H310
    Public Const WM_PALETTECHANGED As Integer = &H311
    Public Const WM_HOTKEY As Integer = &H312
 
    Public Const WM_PRINT As Integer = &H317
    Public Const WM_PRINTCLIENT As Integer = &H318
 
    Public Const WM_HANDHELDFIRST As Integer = &H358
    Public Const WM_HANDHELDLAST As Integer = &H35F
 
    Public Const WM_AFXFIRST As Integer = &H360
    Public Const WM_AFXLAST As Integer = &H37F
 
    Public Const WM_PENWINFIRST As Integer = &H380
    Public Const WM_PENWINLAST As Integer = &H38F
 
    Public Const WM_APP As Integer = &H8000
 
    '
    ' NOTE: All Message Numbers below as Integer = &H400 are RESERVED.
    '
    ' public Window Messages Start Here:
    '
    Public Const WM_USER As Integer = &H400
 
    '  wParam for WM_SIZING message  '
    Public Const WMSZ_LEFT As Integer = 1
    Public Const WMSZ_RIGHT As Integer = 2
    Public Const WMSZ_TOP As Integer = 3
    Public Const WMSZ_TOPLEFT As Integer = 4
    Public Const WMSZ_TOPRIGHT As Integer = 5
    Public Const WMSZ_BOTTOM As Integer = 6
    Public Const WMSZ_BOTTOMLEFT As Integer = 7
    Public Const WMSZ_BOTTOMRIGHT As Integer = 8
 
    '
    ' WM_NCHITTEST and MOUSEHOOKSTRUCT Mouse Position Codes
    '
    Public Const HTERROR As Integer = (-2)
    Public Const HTTRANSPARENT As Integer = (-1)
    Public Const HTNOWHERE As Integer = 0
    Public Const HTCLIENT As Integer = 1
    Public Const HTCAPTION As Integer = 2
    Public Const HTSYSMENU As Integer = 3
    Public Const HTGROWBOX As Integer = 4
    Public Const HTSIZE As Integer = HTGROWBOX
    Public Const HTMENU As Integer = 5
    Public Const HTHSCROLL As Integer = 6
    Public Const HTVSCROLL As Integer = 7
    Public Const HTMINBUTTON As Integer = 8
    Public Const HTMAXBUTTON As Integer = 9
    Public Const HTLEFT As Integer = 10
    Public Const HTRIGHT As Integer = 11
    Public Const HTTOP As Integer = 12
    Public Const HTTOPLEFT As Integer = 13
    Public Const HTTOPRIGHT As Integer = 14
    Public Const HTBOTTOM As Integer = 15
    Public Const HTBOTTOMLEFT As Integer = 16
    Public Const HTBOTTOMRIGHT As Integer = 17
    Public Const HTBORDER As Integer = 18
    Public Const HTREDUCE As Integer = HTMINBUTTON
    Public Const HTZOOM As Integer = HTMAXBUTTON
    Public Const HTSIZEFIRST As Integer = HTLEFT
    Public Const HTSIZELAST As Integer = HTBOTTOMRIGHT
 
    Public Const HTOBJECT As Integer = 19
    Public Const HTCLOSE As Integer = 20
    Public Const HTHELP As Integer = 21
 
    '
    ' SendMessageTimeout values
    '
    Public Const SMTO_NORMAL As Integer = &H0
    Public Const SMTO_BLOCK As Integer = &H1
    Public Const SMTO_ABORTIFHUNG As Integer = &H2
 
    Public Const SMTO_NOTIMEOUTIFNOTHUNG As Integer = &H8
 
    '
    ' WM_MOUSEACTIVATE Return Codes
    '
    Public Const MA_ACTIVATE As Integer = 1
    Public Const MA_ACTIVATEANDEAT As Integer = 2
    Public Const MA_NOACTIVATE As Integer = 3
    Public Const MA_NOACTIVATEANDEAT As Integer = 4
 
    '
    ' WM_SETICON / WM_GETICON Type Codes
    '
    Public Const ICON_SMALL As Integer = 0
    Public Const ICON_BIG As Integer = 1
 
End Module

________
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