Yeah this one is a little tricky. You have to run the game in windowed mode and take a screenshot with PrintScreen (or Alt + PrintScreen to capture only the game window).
For whatever reason (that a real dev can probably explain easily), pressing PrintScreen while the game is in UI/menu mode, and fullscreen, won't capture the screenshot.
Nash wrote:For whatever reason (that a real dev can probably explain easily), pressing PrintScreen while the game is in UI/menu mode, and fullscreen, won't capture the screenshot.
The reason is that in UI mode the system switches to GUI input mode which bypasses the keybind dispatcher (for obvious reasons, you want to control the menu after all...)