[2005] Unusual control move on click with 2 monitors

[jeffnyc]

I have a form that displays a tablelayout panel on a 2nd monitor screen. A form that allows you to control the "look" of the form including the postion of the tablelayout control is on the main screen. The tablelayout panel automatically refreshes by use of a timer.

(side note: I use Application Scoped Settings and I am able to write and store the Application Scoped settings across user using a custom xml routine.)

I have no code in the click event except now I added a write to a log command.

When I shut down the program and restart, the program correctly loads the correct tablelayout position. However, if I single click on the form (on the 2nd screen) the tablelayout panel unexpectedly moves. I have a client machine where I first noticed the error. The client machine also has 2 monitors. I was unable to reproduce the error on my dev machine but as soon as I introduced a 2nd monitor I noticed the error. On my machine both x and y of the tlp location get offset by 6 unexpectly when I click. I don't think this is consistent to the movement on the client machine.

Admittingly, I am an amateur programmer when it comes to VB and VS.net and I don't really know how to use their debugging features which is why I have all these messy writelog statements.

Here is my code from the second form.... (I know its a bit hairy)

Public Class form2
    '  Public t As New System.Timers.Timer(2000)
    Dim curPage As Integer = 0
    Dim numPages As Integer = 0
    Dim pkgCnt As Integer

    Private Sub form2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Click
        frm1.WriteLog("form2 clicked: " & Me.TableLayoutPanel1.Location.ToString)
    End Sub

    Private Sub form2_DoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.DoubleClick
	' note: I have commented out this sub and it appears to have no effect on the error
        If isAdmin Then
            If Me.WindowState = FormWindowState.Maximized Then
                Me.WindowState = FormWindowState.Normal
                Me.FormBorderStyle = Windows.Forms.FormBorderStyle.Sizable
                frm1.btnFormSize.Text = "Set Display Control On"
            Else
                Me.WindowState = FormWindowState.Maximized
                Me.FormBorderStyle = Windows.Forms.FormBorderStyle.None
                frm1.btnFormSize.Text = "Set Display Control Off"
            End If
        End If
    End Sub

    Private Sub form2_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        saveDisplayPosition()
        frm2 = Nothing
    End Sub

    Private Sub form2_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Control.CheckForIllegalCrossThreadCalls = False
        loadImage()
        initTable()
        frm1.WriteLog("form2 loaded: " & Me.TableLayoutPanel1.Location.ToString)
        AddHandler t.Tick, AddressOf TimerFired
    End Sub


    Public Sub initTable()
        Dim x As Int16
        For x = 0 To 19
            Dim label1 As New Label
            With label1
                .Text = ""
                '     .TextAlign = ContentAlignment.MiddleCenter
                .Font = My.Settings.myFont
                .ForeColor = My.Settings.myForeColor
                .BackColor = My.Settings.myBackColor
                .AutoSize = True
            End With
            Me.TableLayoutPanel1.Controls.Add(label1)
        Next
        frm1.WriteLog("inittable end: " & Me.TableLayoutPanel1.Location.ToString)
    End Sub

    Public Sub loadImage()
        Try
            frm2.PictureBox1.Image = Image.FromFile(My.Settings.myImgFile)
        Catch ex As Exception
            Debug.WriteLine("default image used")
        End Try
        frm1.WriteLog("loadImg end: " & Me.TableLayoutPanel1.Location.ToString)
    End Sub

    Public Sub startTimer()
        t.Enabled = True
    End Sub

    Public Sub stopTimer()
        t.Enabled = False
    End Sub

    Public Sub TimerFired(ByVal sender As Object, _
           ByVal e As System.EventArgs)
        frm1.WriteLog("timerfired start: " & Me.TableLayoutPanel1.Location.ToString)
        pkgCnt = frm1.lstApts.CheckedItems.Count
        Dim d As Decimal = (pkgCnt / 20)
        numPages = Decimal.Truncate(d)
        If pkgCnt Mod 20 = 0 And pkgCnt > 0 Then
            numPages = numPages - 1
        End If
        Dim row As Integer = 0
        Dim col As Integer = 0
        Dim curlabel As Label
        Dim sourceIndex As Integer = 0
        Dim sourceArray(pkgCnt - 1) As Object
            frm1.lstApts.CheckedItems.CopyTo(sourceArray, 0)
    
        'special sort
        Me.Cursor = Cursors.WaitCursor
        If (sourceArray.Length - 1 > 0) Then
            'sort alphabetically
            QuickSort(sourceArray, 0, sourceArray.Length - 1)
        End If
        Me.Cursor = Cursors.Default

        ' Me.TableLayoutPanel1.Controls.Clear()

        sourceIndex = (curPage * 20)
        For row = 0 To 3
            For col = 0 To 4
                curLabel = New Label
                curLabel = Me.TableLayoutPanel1.GetControlFromPosition(col, row)
                With curLabel

                    If sourceIndex >= sourceArray.Length Then
                        Text = " "
                    Else
                        .Text = sourceArray(sourceIndex)
                        '        .TextAlign = ContentAlignment.MiddleCenter
                        .Font = My.Settings.myFont
                        .ForeColor = My.Settings.myForeColor
                        .BackColor = My.Settings.myBackColor
                    End If
                End With
                frm1.WriteLog("timerfired loop: " & Me.TableLayoutPanel1.Location.ToString)
                sourceIndex = sourceIndex + 1
            Next
        Next

        If curPage >= numPages Then
               curPage = 0
        Else
              curPage = curPage + 1
        End If
        sourceIndex = 0
        
        frm1.WriteLog("timerfired end: " & Me.TableLayoutPanel1.Location.ToString)
    End Sub


   ' Quicksort stuff removed


    Public Sub saveDisplayPosition()
        Dim x, y As Integer

        If isAdmin Then
            ' save form location
            y = Me.Location.Y
            x = Me.Location.X
            Dim pointStr As String = x & ", " & y
            frm1.ChangeMyAppScopedSetting("myDisplayLoc", pointStr)

            'save image location
            y = Me.PictureBox1.Location.Y
            x = Me.PictureBox1.Location.X
            pointStr = x & ", " & y
            frm1.ChangeMyAppScopedSetting("myImgLoc", pointStr)

            'save table location
            y = Me.TableLayoutPanel1.Location.Y
            x = Me.TableLayoutPanel1.Location.X
            pointStr = x & ", " & y
            frm1.ChangeMyAppScopedSetting("myLocation", pointStr)
            frm1.WriteLog("saved location sdp: " & Me.TableLayoutPanel1.Location.ToString)

            ' save displays window state
            Dim wsStr As String = Me.WindowState.ToString
            frm1.ChangeMyAppScopedSetting("myDisplayWinState", wsStr)
           
           ' save borderstyle
            Dim brdrStr As String = Me.FormBorderStyle.ToString
            frm1.ChangeMyAppScopedSetting("myDisplayBorder", brdrStr)
        End If
    End Sub
End Class

Here is the snapshot from the log which shows the unexpected change:

2007-12-30 13:01:18 inittable end: {X=251,Y=-27}
2007-12-30 13:01:18 form2 loaded: {X=251,Y=-27}
2007-12-30 13:01:18 loaded location: {X=176,Y=262} ' this was the saved app setting correctly loaded
2007-12-30 13:01:22 timerfired end: {X=176,Y=262}
2007-12-30 13:01:24 form2 clicked: {X=170,Y=256} ' this is the unexpected change
2007-12-30 13:01:24 timerfired start: {X=170,Y=256}

I know this bug might be a pain to help with but any tips would be greatly appreciated because I have been stuck with this bug for quite some time. Thanks in advance.

[jmcilhinney]

I would suggest handling the LocationChanged event of the TLP, set a breakpoint and examine the call stack. Hopefully it can show you where the property change occurred.