I was playing with the font color this morning, and thought I would try something...
I wanted to see how yellow looked when I typed something, and previewed it. (This was the result.
And then I wanted to see how white looked, but it wasn't available in the drop down list. So I did yellow again, and replaced the word yellow with the word white. (This was the result.
Which gave me a GREAT idea... and I changed the color of the font again, but this time used the word transparent. (This was the result.
Highlight the text inside the parentheses to see what I wrote.
It looks like we CAN make text invisible when it is a spoiler, or potentially squeamish to other posters! It just isn't an option in the drop down list! Hooray!