elisp: Button Types
37.19.2 Button Types
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Every button has a “button type”, which defines default values for the
button’s properties. Button types are arranged in a hierarchy, with
specialized types inheriting from more general types, so that it’s easy
to define special-purpose types of buttons for specific tasks.
-- Function: define-button-type name &rest properties
Define a button type called NAME (a symbol). The remaining
arguments form a sequence of PROPERTY VALUE pairs, specifying
default property values for buttons with this type (a button’s type
may be set by giving it a ‘type’ property when creating the button,
using the ‘:type’ keyword argument).
In addition, the keyword argument ‘:supertype’ may be used to
specify a button-type from which NAME inherits its default property
values. Note that this inheritance happens only when NAME is
defined; subsequent changes to a supertype are not reflected in its
subtypes.
Using ‘define-button-type’ to define default properties for buttons
is not necessary—buttons without any specified type use the built-in
button-type ‘button’—but it is encouraged, since doing so usually makes
the resulting code clearer and more efficient.
Info Catalog
elisp: Button Properties
elisp: Buttons
elisp: Making Buttons