11.10 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. On most window systems, the help
text is displayed as a “tooltip” (sometimes known as “balloon
help”), when you move the mouse over the active text. See Tooltips.
On some systems, it is shown in the echo area. On text-only
terminals, Emacs may not be able to follow the mouse and hence will
not show the help text on mouse-over.
You can also access text region help info using the keyboard. The
command C-h . (
display-local-help) displays any help text
associated with the text at point, using the echo area. If you want
help text to be displayed automatically whenever it is available at
point, set the variable