http://whatis.techtarget.com/definition/0,,sid9_gci212806,00..."A pop-up is a graphical user interface ( GUI ) display area, usually a small window, that suddenly appears ("pops up") in the foreground of the visual interface. Pop-ups can be initiated by *****a single or double mouse click or rollover**** (sometimes called a mouseover)".
http://www.webopedia.com/TERM/P/pop_up_window.html"A window that suddenly appears (pops up) when you ****select an option with a mouse or press a special function key****.... A special kind of pop-up window is a pull-down menu, which appears just below the item you selected, as if you had pulled it down."
If you're sure about the modality in which the text appears, you might want to use a more specific term, like pull-down text.
peer agreement (net): +3