RE: Problem when showing MdiChild form

Hi Lance,

During the discussion, the Winform confirmed that there is some painting
logic order wrong in showing the MDI child form. It seems that the
problematic drawing embeded deep in the Layout code. After spending a lot
effect to find a workaround, one Winform developer is able to find a
workaround. The workaround logic is like this:
"Basically, when you create the childform, set its position to (-1000,
-1000) (outside the screen). After it is set to visible, then you put it
back in the correct spot. When you set it to visible=false, then set it
outiside the screen again."
The modified repro sample is listed below, you may give it a try:

Public Class Form1
Inherits Windows.Forms.Form

Protected WithEvents Button1 As Windows.Forms.Button
Protected ChildForms() As Windows.Forms.Form

Public Sub New()
MyBase.New()
Me.IsMdiContainer = True
Me.Size = New Drawing.Size(800, 600)

Const n As Integer = 4
Const uBound As Integer = (n - 1)
Dim childForms(uBound) As Windows.Forms.Form
Dim position As Integer = 0
Const delta As Integer = 24
For i As Integer = 0 To uBound
childForms(i) = New Windows.Forms.Form
childForms(i).MdiParent = Me
childForms(i).FormBorderStyle = Windows.Forms.FormBorderStyle.None
childForms(i).ControlBox = False
childForms(i).StartPosition = FormStartPosition.Manual
childForms(i).Location = New Drawing.Point(position-1000, position-1000)
position += delta
Next i
Me.ChildForms = childForms

Me.Button1 = New Windows.Forms.Button
Me.Button1.Text = "Click Me"

Dim topPanel As New Windows.Forms.Panel
topPanel.Height = Me.Button1.Height
topPanel.Dock = DockStyle.Top
topPanel.Controls.Add(Me.Button1)

Me.Controls.Add(topPanel)
End Sub

Private Sub Button1_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Button1.Click
For i As Integer = 0 To Me.ChildForms.GetUpperBound(0)
Me.ChildForms(i).Visible = (Not Me.ChildForms(i).Visible)
If Me.ChildForms(i).Visible Then
Me.ChildForms(i).Location = New Drawing.Point(Me.ChildForms(i).Location.X +
1000, Me.ChildForms(i).Location.Y + 1000)
Else
Me.ChildForms(i).Location = New Drawing.Point(Me.ChildForms(i).Location.X -
1000, Me.ChildForms(i).Location.Y - 1000)
End If
Next i
End Sub

Protected Overrides Sub OnMdiChildActivate(ByVal e As System.EventArgs)
' The following simulates code that might be executed when an MdiChild is
activated, such as merging menus.
Dim duration As New System.TimeSpan(0, 0, 1)
Dim startTime As System.DateTime = System.DateTime.Now
While ((System.DateTime.Now - startTime) < duration)
End While
MyBase.OnMdiChildActivate(e)
End Sub

End Class

Hope this helps.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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