Button Properties

Each button has an associated list of properties defining its appearance and behavior, and other arbitrary properties may be used for application specific purposes. The following properties have special meaning to the Button package:

action

The function to call when the user invokes the button, which is passed the single argument button. By default this is ignore, which does nothing.

mouse-action

This is similar to action, and when present, will be used instead of action for button invocations resulting from mouse-clicks (instead of the user hitting RET). If not present, mouse-clicks use action instead.

face

This is an Emacs face controlling how buttons of this type are displayed; by default this is the button face.

mouse-face

This is an additional face which controls appearance during mouse-overs (merged with the usual button face); by default this is the usual Emacs highlight face.

keymap

The button’s keymap, defining bindings active within the button region. By default this is the usual button region keymap, stored in the variable button-map, which defines RET and mouse-2 to invoke the button.

type

The button type. See Button Types.

help-echo

A string displayed by the Emacs tooltip help system; by default, "mouse-2, RET: Push this button". Alternatively, a function that returns, or a form that evaluates to, a string to be displayed or nil. For details see Text help-echo.

The function is called with three arguments, window, object, and pos. The second argument, object, is either the overlay that had the property (for overlay buttons), or the buffer containing the button (for text property buttons). The other arguments have the same meaning as for the special text property help-echo.

follow-link

The follow-link property, defining how a mouse-1 click behaves on this button, See Clickable Text.

button

All buttons have a non-nil button property, which may be useful in finding regions of text that comprise buttons (which is what the standard button functions do).

There are other properties defined for the regions of text in a button, but these are not generally interesting for typical uses.