G.9 Help on Active Text and Tooltips

When a region of text is "active," so that you can select it with the mouse or a key like RET, it often has associated help text. Areas of the mode line are examples. This help will normally be shown in the echo area when you move point into the active text. In a window system you can display the help text as a "tooltip" (sometimes known as "balloon help"). See section P.18 Tooltips (or "Balloon Help").