I modified the example in the help file.... 
Essentially, everytime the function runs, it can read a $Model that gets returned earlier, and display that image.  However, the previous image does not seem to go away. 
_GDIPlus_GraphicsDispose($g_hGraphic) 
_GDIPlus_ImageDispose($g_hImage) 
  
Do not seem to work, and $RDW_ERASENOW seems to have do nothing. 
; Draw PNG image
Func MY_WM_PAINT($hWnd, $iMsg, $wParam, $lParam)
    #forceref $hWnd, $iMsg, $wParam, $lParam
If _GDIPlus_ImageLoadFromFil