Image Animation Help

[icedece]

Hi guys

i'm currently creating a vb6 version of the arcade game "Stacker"
http://en.wikipedia.org/wiki/Stacker_(game)

The above link will give a detailed version of what i'm trying to create however for those who just want a rundown here it is:

There is a row of three cubes which move side to side on the screen, at the first row. When the player pushes the start/stop button, the row of squares will stop. Then, another row of three moving squares appears above the previous row, moving faster than the one before it. If the squares do not align directly above the previous set, any overhanging squares will be removed. If the player misses completely, the game is over. The number of available squares is automatically reduced to two, then one, during the game. The goal is to consistently get the squares directly above the previous set, "stacking" them to the minor prize and ultimately major prize levels.
In this case however the prizes will be replaced by points.

At the moment i'm having trouble figuring out the code for animation reversal when the blocks hit the side of the screen and change direction.

Dim Block(2) As BlockPart

'Sets the initial value of the block

Private Sub Form_Load()

Dim i As Long
length = 3
For i = 0 To 2
Block(i).X = (95 - 34 * i)
Block(i).Y = 410
ImgBlock(i).Left = Block(i).X
ImgBlock(i).Top = Block(i).Y
Block(i).Facing = 3
Next i

End Sub



Private Sub TmrMove_Timer()
Dim i As Integer 'counter
For i = 0 To 2 'for each frame
ImgBlock(i).Left = ImgBlock(i).Left + 10 'move it right 10
Next i
If ImgBlock(0).Left + ImgBlock(0).Width > ImgBackground.Width Then 'if at the edge of screen
TmrMove.Enabled = False 'stop timer
End If
End Sub


Private Sub CmdGo_Click()

TmrMove.Enabled = True 'enable the timer

End Sub

Any help here would be greatly appreciated
and thanks in advance