1. Overview

I should be pretty obvious what buttons are and where they are usually used. One thing one should keep in mind is the fact that ../GtkButton is used inside other widgets like ../GtkComboBox, ../GtkTreeView and ../GtkOptionMenu.

2. Style Properties

Name	Default	Description
default-border	`{1, 1, 1, 1}`	Extra space to add for CAN_DEFAULT buttons
default-outside-border	`{0, 0, 0, 0}`	Extra space to add for CAN_DEFAULT buttons that is always drawn outside the border
child-displacement-x	0	How far in the x direction to move the child when the button is depressed
child-displacement-y	0	How far in the y direction to move the child when the button is depressed
displace-focus	FALSE	Whether the child_displacement_x/_y properties should also affect the focus rectangle
inner-border	`{1, 1, 1, 1}`	Border between button edges and child.

Values given in the form {1, 1, 1, 1} map as {left, right, top, bottom}.

3. Geometry

3.0.1. Geometry if interior-focus = 1

The geometry of a simple button that cannot get the default action:

3.0.2. interior-focus = 0

If interior-focus = 0, then the focused button will look differently. (Buttons without a focus stay the same.)

TODO: show spacing for the HAS_DEFAULT case.

4. Drawing

Buttons may be drawn transparent.

As seen in the above images, the button consists of a BOX. If the button has the focus, it will be drawn on the button as schown in the above images. The detail for both of these is "button".

There is nothing special about the state and shadow that are used:

	normal	pressed	prelight	insensitive
shadow type	OUT	IN	OUT	OUT
state	NORMAL	ACTIVE	PRELIGHT	INSENSITIVE

If the button is the default button, then another box with detail "buttondefault" will be drawn underneath everything.

5. How to Change Button on focus style

It seems only accept change focus line width and color, if it can change the background image.

6. GTK+ API Documentation

http://library.gnome.org/devel/gtk/stable/GtkButton.html