User guide

138 Painting, Drawing, and Text
Applying a gradient fill on any kind of layer entails selecting one of the fill types,
editing the fill colors and/or transparency in a Gradient dialog, then applying the
fill. However, gradient fills behave differently depending on the kind of layer
you're working on.
On standard and Background layers,
the tool creates a "spectrum" effect, filling
the active layer or selection with colors
spreading between the key colors in the
selected gradient fill. The fill is applied
rather like a coat of spray paint over
existing pixels on the layer; color and
transparency properties in the fill
gradient interact with the existing pixels
to produce new values. In other words,
once you've applied the fill, you can't go
back and edit it (except by undoing it
and trying again).
Transparency works in a comparable way, affecting how much the paint you
apply is "thinned." At full opacity, the fill completely obscures pixels underneath.
On text and shape layers, the Gradient
Fill Tool is even more powerful—the
fill’s color and transparency properties
remain editable. Technically, the fill is a
property of the layer, and the shape(s)
act as a "window" enabling you to see the
fill. Thus a single fill applies to all the
shapes on a particular layer—note the
gradient fill opposite which is applied
across three QuickShapes present on the
same layer.
Transparency gradients determine which portions of the object you can see
through. Note that the Flood Fill Tool doesn't work with text or shapes. When
first drawn, a shape takes a Solid fill using the foreground color. You can change
the fill type as described below.