Quote Originally Posted by Shohag_ifas View Post
...
Let say:
there is 3 picture box
when i click on a button picture1 drawn on picture3
now to do the effect again i set pic3=pic2
and click the button again. it's drawn the pic on on pic3
but the issue is it also change pic2 to pic1 (or may be to pic3) why
....
pic3 is a reference to an object.
pic2 is a reference to an object.
pic3 = pic2
Now pic3 and pic2 reference the same object, the one pic2 was referencing.
Since they both "point" to the same thing, you can use pic3 or pic2 to change the underlying object.

Perhaps you want to make a copy of the image using the Clone method, something like
PictureBox3.Image = CType(PictureBox2.Image.Clone,Image) REM to load another image on pic3 to set pic 1 again

Or perhaps, redraw the image
Code:
Using g as Graphics = Graphics.FromImage(PictureBox3.Image)
  g.DrawImage(PictureBox2.Image,0,0)
End Using