i'm trying learning directx with vb6.
i have these code for work with fullscreen:
Code:
Public Function Initialise() As Boolean
    On Error GoTo ErrHandler:
    Dim DispMode As D3DDISPLAYMODE '//Describes our Display Mode
    Dim D3DWindow As D3DPRESENT_PARAMETERS '//Describes our Viewport
    Set Dx = New DirectX8 '//Create our Master Object
    Set D3D = Dx.Direct3DCreate() '//Make our Master Object create the Direct3D Interface
    DispMode.Format = D3DFMT_X8R8G8B8
    DispMode.Width = 640
    DispMode.Height = 480
    D3DWindow.SwapEffect = D3DSWAPEFFECT_FLIP
    D3DWindow.BackBufferCount = 1 '//1 backbuffer only
    D3DWindow.BackBufferFormat = DispMode.Format 'What we specified earlier
    D3DWindow.BackBufferHeight = 480
    D3DWindow.BackBufferWidth = 640
    D3DWindow.hDeviceWindow = Form1.hWnd
    Set D3DDevice = D3D.CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, Form1.hWnd, D3DCREATE_SOFTWARE_VERTEXPROCESSING, D3DWindow)
    Initialise = True '//We succeeded
    Exit Function
ErrHandler:
    '//We failed; for now we wont worry about why.
    Initialise = False
End Function
these code works fine. well except when we close the program
heres the rest of code:
Code:
Option Explicit

'//The variables Required
Dim Dx As DirectX8 'The master Object, everything comes from here
Dim D3D As Direct3D8 'This controls all things 3D
Dim D3DDevice As Direct3DDevice8 'This actually represents the hardware doing the rendering
Dim bRunning As Boolean 'Controls whether the program is running or not...


'//These aren't really required - they'll just show us what the frame rate is...

Private Declare Function GetTickCount Lib "kernel32" () As Long '//This is used to get the frame rate.
Dim LastTimeCheckFPS As Long '//When did we last check the frame rate?
Dim FramesDrawn As Long '//How many frames have been drawn
Dim FrameRate As Long '//What the current frame rate is.....

Public Sub Render()
    '//1. We need to clear the render device before we can draw anything

    'This must always happen before you start rendering stuff...
    D3DDevice.Clear 0, ByVal 0, D3DCLEAR_TARGET, D3DColorRGBA(0, 0, 255, 255), 1#, 0
    '1. the D3DColorRGBA() is for give us a color. in these case i use the blue color. i don't use
    'the alpha value, that's why i put 255.

    '//2. Next we would render everything. This lesson doesn't do this, but if it did it'd look something
    'like this:
    D3DDevice.BeginScene

        'All rendering calls go between these two lines

    D3DDevice.EndScene

    '//3. Update the frame to the screen...

    'This is the same as the Primary.Flip method as used in DirectX 7

    'These values below should work for almost all cases...

    D3DDevice.Present ByVal 0, ByVal 0, 0, ByVal 0

End Sub

Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
    If KeyCode = vbKeyEscape Then bRunning = False
End Sub

Private Sub Form_Load()
    Me.Show '//Make sure our window is visible
    bRunning = Initialise()
    Debug.Print "Device Creation Return Code : ", bRunning 'So you can see what happens...
    
    Do While bRunning
        Render '//Update the frame...
        DoEvents '//Allow windows time to think; otherwise you'll get into a really tight (and bad) loop...
        'Calculate the frame rate; how this is done isn't greatly important
        'So dont worry about understanding it yet...

        If GetTickCount - LastTimeCheckFPS >= 1000 Then
            LastTimeCheckFPS = GetTickCount
            FrameRate = FramesDrawn '//Store the frame count
            FramesDrawn = 0 '//Reset the counter
            Me.Caption = "DirectX-Graphics: Lesson 01   {" & FrameRate & "fps}" '//Display it on screen
        End If
        FramesDrawn = FramesDrawn + 1
    Loop
    '//If we've gotten to this point the loop must have been terminated
    'So we need to clean up after ourselves. This isn't essential, but it'
    'good coding practise.
    On Error Resume Next 'If the objects were never created;
    '(the initialisation failed) we might get an
    'error when freeing them... which we need to
    'handle, but as we're closing anyway...
    Set D3DDevice = Nothing
    Set D3D = Nothing
    Set Dx = Nothing
    Debug.Print "All Objects Destroyed"
    '//Final termination:
    Unload Me
    End

End Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
    bRunning = False
End Sub
why, when we close the program, the vb6 IDE and other programs change their window(and some controls) size?