KDE has very cool capabilities to do very fast gradient rendering. Of course this is also utilized by the widget theme plugin.
To make widgets use automatic gradients you need to set three keys in the widget's configuration group. This includes the "Gradient" key which describes the type of gradient to use, the "GradientHigh" key which describes the high color for the gradient, and the "GradientLow" key which describes the low color. The following is an example configuration:
As noted above, the "Gradient" key specifies what type of gradient to use. Here is a list of the valid values and a small picture of how they look:
Gradient=Diagonal
Gradient=Vertical
Gradient=Horizontal
Gradient=Elliptic
Gradient=Pyramid
Gradient=Rectangle
Next we will go over using pixmaps instead of gradients for widgets.