SDL_ShowSimpleMessageBox input treatment

On Linux under X any newline character in the message passed to this
function is interpreted as the beginning of a new line, while a
carriage return character in the message is interpreted as a new
paragraph (possibly two new lines). There is no automatic text
wrapping, so without these characters a window possibly wider than the
display will be created to show a continuous line of text. In
addition, the tab character produces an N over L (I’m guessing Not
Legal) glyph and is otherwise ignored.

Is this behavior consistent across platforms and with other display
servers that SDL works with?