pictureBox画线有关问题

pictureBox画线问题请问我在PictureBox上画线之后,然后在里面话线组成的网格内画点,我想做一个按钮,按一下

pictureBox画线问题
请问我在PictureBox上画线之后,然后在里面话线组成的网格内画点,我想做一个按钮,按一下画出网格,再按一些网格消失,但里面画的点不能消失。

[解决办法]
Option Explicit
Dim i As Integer
Private Sub Command1_Click() '用vbBlue画格
For i = 1 To 12
Picture1.Line (500, i * 500)-(12000, i * 500), vbBlue
Next
For i = 1 To 24
Picture1.Line (i * 500, 500)-(i * 500, 6000), vbBlue
Next
End Sub

Private Sub Command2_Click() '用Picture1的底色清除vbBlue画格
For i = 1 To 12
Picture1.Line (500, i * 500)-(12000, i * 500), &H8000000F
Next
For i = 1 To 24
Picture1.Line (i * 500, 500)-(i * 500, 6000), &H8000000F
Next
End Sub