$StartCopyButton.Add_Click({
    $script:CancelLoop = $false
    $CancelButton.Enabled = $true
    $StartCopyButton.Enabled = $false

    Get-ChildItem -LiteralPath $Source -Recurse -File | ForEach {
        Copy-Item -Path $.FullName -Destination $NewDestination
        [System.Windows.Forms.Application]::DoEvents()
        If($script:CancelLoop -eq $true) {
            #Exit the loop
            Break;
        }
    }
    $CancelButton.Enabled = $false
    $StartCopyButton.Enabled = $true
})

$CancelButton.Add_Click({
    $script:CancelLoop = $true
})