A script that enables you to use Alt+F4 to exit the PowerShell instance.

AltF4ToExit.ps1

Set-PSReadLineKeyHandler -Key 'Alt+F4' `
                         -BriefDescription ExitPowerShell `
                         -LongDescription "Exits PowerShell" `
                         -ScriptBlock {
    param($key, $arg)
	
    $line = $null;
    $cursor = $null;
    [Microsoft.PowerShell.PSConsoleReadLine]::GetBufferState([ref] $line, [ref] $cursor);
    [Microsoft.PowerShell.PSConsoleReadLine]::Delete(0, $line.Length);
	
    [Microsoft.PowerShell.PSConsoleReadLine]::Insert("exit");
    [Microsoft.PowerShell.PSConsoleReadLine]::AcceptLine($null, $null);
}