listbox has dotted line inside it which I don't want to show

here is my code for a listbox. when you click on the form it shows a dotted outline at the top of the listbox. I would like to remove it.

[reflection.assembly]::loadwithpartialname("System.Windows.Forms") | Out-Null
[reflection.assembly]::loadwithpartialname("System.Drawing") | Out-Null

$form = New-Object System.Windows.Forms.Form
$form.Text = "test"
$drawing_size = New-Object System.Drawing.Size
$drawing_size.Width = 350
$drawing_size.Height = 300
$form.Size = $drawing_size


$listbox1 = New-Object system.windows.forms.listbox
$System_Drawing_Size = New-Object System.Drawing.Size
$System_Drawing_Size.Width = 301
$System_Drawing_Size.Height = 212
$listBox1.Size = $System_Drawing_Size
$System_Drawing_Point = New-Object System.Drawing.Point
$System_Drawing_Point.X = 13
$System_Drawing_Point.Y = 13
$listBox1.Location = $System_Drawing_Point
$form.Controls.Add($listBox1)

$form.ShowDialog() | Out-Null

here it a link to the screen shot
https://copy.com/dIxqL4gdBFo1WnSp

It’s doing that because the list box has focus; the dotted line is showing you where your keyboard will start doing stuff if you press space, tab, etc. If your form has other elements, you can give one of those focus instead, but in this small example where the ListBox is your only control, you can just set the list box’s TabStop property to False to get a similar result:

$listbox1.TabStop = $false

Ahh. Thanks!