To add spoilers to content use the "Sp" tag at the far right->second row->third from the end.
To use, type your text, highlight it and then click that "Sp" tag. You should now have content that can be revealed.
Spoiler
Whoo Hoo testing that spoiler tag...
Quoting text can be tricky if it is a copy and paste from somewhere else. What I have found is that those pesky ellipse, apostrophes and quotes are in the text which in turn don't get saved or posted.
So when cutting and pasting watch the "" '' and the ... and the -
