Focus setzen

Hallo, wie erreiche ich es, dass der Cursor im Eingabefeld steht und ich sofort nach dem Scriptstart meinen Text eingeben kann?

[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing") 
    [void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") 
    $objForm = New-Object System.Windows.Forms.Form 
    $objForm.Text = "LBBW DSM Support"
    $objForm.Size = New-Object System.Drawing.Size(300,200) 
    $objForm.StartPosition = "CenterScreen"
    $objForm.KeyPreview = $True
    $objForm.Add_KeyDown({if ($_.KeyCode -eq "Enter") 
        {$x=$objTextBox.Text;$objForm.Close()}})
    $objForm.Add_KeyDown({if ($_.KeyCode -eq "Escape") 
        {$objForm.Close()}})
    $OKButton = New-Object System.Windows.Forms.Button
    $OKButton.Location = New-Object System.Drawing.Size(75,120)
    $OKButton.Size = New-Object System.Drawing.Size(75,23)
    $OKButton.Text = "Senden"
    $OKButton.Add_Click({$x=$objTextBox.Text;$objForm.Close()})
    $objForm.Controls.Add($OKButton)
    $CancelButton = New-Object System.Windows.Forms.Button
    $CancelButton.Location = New-Object System.Drawing.Size(150,120)
    $CancelButton.Size = New-Object System.Drawing.Size(75,23)
    $CancelButton.Text = "Abbrechen"
    $CancelButton.Add_Click({$objForm.Close()})
    $objForm.Controls.Add($CancelButton)
    $objLabel = New-Object System.Windows.Forms.Label
    $objLabel.Location = New-Object System.Drawing.Size(10,20) 
    $objLabel.Size = New-Object System.Drawing.Size(280,20) 
    $objLabel.Text = "Bitte den Computernamen eingeben:"
    $objForm.Controls.Add($objLabel) 
    $objTextBox = New-Object System.Windows.Forms.TextBox 
    $objTextBox.Location = New-Object System.Drawing.Size(10,40) 
    $objTextBox.Size = New-Object System.Drawing.Size(260,20) 
    $objForm.Controls.Add($objTextBox) 
    $objForm.Topmost = $True
    $objForm.Add_Shown({$objForm.Activate()})
    [void] $objForm.ShowDialog()
    $computername = $x

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