Operation Manual

110 Colour, Fills, and Transparency
The higher the percentage value assigned to a transparency handle,
the more transparent the effect at that point. Note: The hue of the
colour doesn't matter, only its percentage value—so it's much easier
just to choose from the set of gallery thumbnails.
4. To change the transparency value of any existing handle, including
the start and end handles, select the handle and click on a new
thumbnail in the Transparency tab's Solid transparency gallery (you
can also drag your chosen thumbnail onto the selected handle).
5. To move a handle you've added, simply drag it to a new position
along the transparency path.
6. To delete a handle you've added, select it and press the Delete key.