What is a GTK Engine?
GTK has about 20 few drawing functions internally, which can be overridden by the GTK engine. GTK itself has only a very basic implementation for these drawing functions, and all widgets have the same 3d look to them. GTK engines override the buildin functions used by GTK. This enables them to draw whatever they want.
The Pixmap Approach
Every aspect of every widget is drawn from a user-specifiable pixmap image. Popular engines in this grouping are:
The Single-Look Approach
A single, uniform look is used for all widgets; generally only allowing for color variations or minor changes to widget style. Some of the more well known engines in this grouping are:
The Flexible Approach
The engine internally allows for multiple ways of drawing things so the user can configure it to draw what he wants but it doesn't have the overhead of pixmap images. The engines in this category are: