Guides (guide lines) are visible in perspective views at some view angles and invisible at other angles. It seems to be a bug, but Pascal Golay believes that this bug probably cannot be fixed, so it is a limitation, rather than a bug. If it is a limitation, it would be good idea to mention it in documentation. more info is here: Rhino 6.10 - Guide display bug
Another AddGuide bug: Undo does not undo/remove AddGuide.
_______________________________________________________________
TiltView documentation file is posted here: https://docs.mcneel.com/rhino/6/help/en-us/commands/tiltview.htm
It says: The view rotation snaps in five-degree increments. The keyboard shortcut, Shift + Alt + Right mouse button displays an “s” to indicate the snap mode is on.
In reality, Rhino displays digit 5 rather than letter s. Windows 10 cannot take a screenshot of this digit, but I looked at it through magnifying glass and I have seen digit 5 with great clarity.