Excel Application does not repaint itself when automated
from VB.NET using the following code.
1. Open New Windows Application Project in VB.Net 2003.
2. Add COM Reference to Microsoft Excel 10 Library.
3. Add Form1 to the project.
4. Add Form2 to the project.
5. Add Button control to Form1.
6. Insert the following code in Form1:

Private Sub Button1_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles Button1.Click
xl = New
Microsoft.Office.Interop.Excel.ApplicationClass

' Create a command bar
Dim toolBar As Microsoft.Office.Core.CommandBar =
Nothing
toolBar = CType(xl.CommandBars.Add("NLC CASA
Toolbar",
Microsoft.Office.Core.MsoBarPosition.msoBarTop, , True),
Microsoft.Office.Core.CommandBar)
toolBar.Visible = True

'create new button
newButton = CType(toolBar.Controls.Add
(Microsoft.Office.Core.MsoControlType.msoControlBu tton),
Microsoft.Office.Core.CommandBarButton)
newButton.Caption = "Insert Input Element"
newButton.FaceId = 88
'AddHandler newButton.Click, AddressOf
ShowCustomForm

wkb = xl.Workbooks.Add
xl.EnableEvents = True
xl.Visible = True

End Sub

Private Sub newButton_Click(ByVal Ctrl As
Microsoft.Office.Core.CommandBarButton, ByRef
CancelDefault As Boolean) Handles newButton.Click
Dim frm As New Form2
frm.TopMost = True
frm.ShowDialog()
End Sub

7. When Application runs press button (Excel will be open).
8. In Excel press newly created button, which shows 'I' in
it (Form2 opens on top).
9. If you move Form2 Excel does not repaint itself.

I even tried using Windows API. It does not help...