Key-combination "Alt+Tab": getting number of programs in this list

When we press the keys “Alt+Tab” in Windows 7, we can see a list with all open programs.

Is there a command we can use, to get how many programs are in this list? Or if this list still contains programs or if it is empty?

I have found this:

$ProcessName = "calc"
$Program = "calc.exe"
$CheckProcess = ""
$CheckProcess = Get-Process | Where-Object {$_.ProcessName -eq $ProcessName}
If($CheckProcess -eq $null){
////make something////
}
else {
//////make something else////////
}

But I am not interested in particular processes. Just interested in the processes that are in the list that we get with the key combination “Alt+Tab”. And here actually only in the number of open programs from this list.

Is there a way to get this?

Would appreciate some help. Thank you.