Npcap installer shows brief black window

[dmiller-nmap]

The Npcap installer sometimes flashes a small window for a brief second, even when using the silent install option. We believe this is related to the use of _tpopen to run commands from NPFInstall.exe.

[dmiller-nmap]

There is also a brief "file copy" window that flashes during installation of the WFP callout driver. This doesn't seem to be avoidable, but I will research a bit more.

[dmiller-nmap]

I believe the file copy window is a result of the CopyFiles directive in the INF files being used to copy the npcap.sys driver into the %SYSTEMROOT%\System32\Drivers directory. We may be able to avoid this by having our installer copy the files instead; if we use the right flags to avoid the copy operation if the file exists and is newer, then we might be able to hide this screen.