FIX: Setting Windowless Control to Transparent Prevents Animation

View products that this article applies to.

This article was previously published under Q257645

SYMPTOMS

When you set the BackStyle property of a windowless control to Transparent, animation effects for that control are prevented from taking place. The effects are drawn, but they are not animated.

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CAUSE

This behavior is due to the way Visual Basic draws controls.

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Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article. This bug was corrected in the latest service pack for Visual Studio 6.0.

For additional information about Visual Studio service packs, click the following article numbers to view the articles in the Microsoft Knowledge Base:

194022 (http://support.microsoft.com/kb/194022/EN-US/ ) INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 (http://support.microsoft.com/kb/194295/EN-US/ ) HOWTO: Tell That a Visual Studio Service Pack Is Installed

To download the latest Visual Studio service pack, visit the following Microsoft Web site:

http://msdn2.microsoft.com/en-us/vstudio/Aa718353.aspx (http://msdn2.microsoft.com/en-us/vstudio/Aa718353.aspx)

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MORE INFORMATION

Steps to Reproduce Behavior

Create a new ActiveX Control project in Visual Basic. UserControl1 is created by default.
Change the Height and Width property of UserControl1 to 1680.
Change the Windowless property of UserControl1 to True.

Add the following code to UserControl1:

Option Explicit

Private x As Long
Private y As Long

Public Property Get BackStyle() As Integer
    BackStyle = UserControl.BackStyle
End Property

Public Property Let BackStyle(ByVal New_BackStyle As Integer)
    UserControl.BackStyle() = New_BackStyle
    PropertyChanged "BackStyle"
End Property

Public Property Get BackColor() As OLE_COLOR
    BackColor = UserControl.BackColor
End Property

Public Property Let BackColor(ByVal New_BackColor As OLE_COLOR)
    UserControl.BackColor() = New_BackColor
    PropertyChanged "BackColor"
End Property

Private Sub UserControl_Initialize()
    x = Width
    y = x
End Sub

Private Sub UserControl_Paint()
    If Ambient.UserMode = False Then Exit Sub
    Randomize
    Dim i As Integer
    Dim j As Integer
    For j = 1 To 40
        For i = 1 To 30000
            If i Mod 10000 = 0 Then
                Circle (x * Rnd, y * Rnd), 50
            End If
        Next
    Next
End Sub

' Load property values from storage
Private Sub UserControl_ReadProperties(PropBag As PropertyBag)

    UserControl.BackStyle = PropBag.ReadProperty("BackStyle", 1)
    UserControl.BackColor = PropBag.ReadProperty("BackColor", &H8000000F)
End Sub

' Write property values to storage
Private Sub UserControl_WriteProperties(PropBag As PropertyBag)

    Call PropBag.WriteProperty("BackStyle", UserControl.BackStyle, 1)
    Call PropBag.WriteProperty("BackColor", UserControl.BackColor, &H8000000F)
End Sub

From the File menu, select Add Project. Choose Standard EXE and click Open. Form1 is created by default.
Close the (designer) window for UserControl1.
Add two instances of UserControl1 to Form1. They are named UserControl11 and UserControl12.
Change the BackColor property of both UserControls to something other than grey.
In the Project Explorer, change the startup project by right-clicking on Project2. Select Set as Startup.
Press the F5 key to run the project. Note that you can see circles being drawn on the controls (animation.)
Stop the project and change the BackStyle property of UserControl12 to 0 (Transparent.)
Press F5 to run, and note that you do not see the circle animation on UserControl11. The form becomes transparent while animating, but you only see the circles on the control after the animation has taken place.