NSEvent.addGlobalMonitorForEvents() cannot capture the Cmd-Shift-3 (Screenshot)

Hi,

What I want to do is displaying all keystroke on screen. (Just like the built-in Keyboard Viewer)

I use NSEvent.addGlobalMonitorForEvents() and maintain a set of pressed keys.

Most keystroke are fine. However, Cmd-Shift-3, Cmd-Shift-4 cannot be captured.

Is there any way to capture all keyboard event?

Regards,

hypoDev