Public/Add-WPFListBoxItem.ps1

function Add-WPFListBoxItem
{
<#
    .SYNOPSIS
        Function to add items from a Listbox
     
    .DESCRIPTION
        Function to add items from a Listbox.
     
        System.windows.controls.listbox
        https://msdn.microsoft.com/en-us/library/system.windows.controls.listbox(v=vs.110).aspx
     
    .PARAMETER ListBox
        Specifies the Listbox control
     
    .PARAMETER Items
        Specifies the items to add in the Listbox
     
    .PARAMETER Append
        Specifies that the Listbox
         
    .NOTES
        Francois-Xavier Cat
        lazywinadmin.com
        @lazywinadm
        github.com/lazywinadmin
#>

    Param (
        [ValidateNotNull()]
        [Parameter(Mandatory = $true)]
        [System.Windows.Controls.ListBox]
        $ListBox,
        
        [ValidateNotNull()]
        [Parameter(Mandatory = $true)]
        $Item #,
        
        #[Switch]$Append=$true
        
    )
    BEGIN
    {
        Add-Type –assemblyName PresentationFramework
        Add-Type –assemblyName PresentationCore
        Add-Type –assemblyName WindowsBase
    }
    PROCESS
    {
        <#
        IF (-not $PSBoundParameters['Append'])
        {
            # Clear ListBox
            $ListBox.items.Clear()
        }
        #>

        
        # Add Items
        FOREACH ($i in $Item)
        {
            $ListBox.Items.Add($i)
        }
    }
}