[5.9] How do I create non-rectangular buttons?

Usually, a sprite will respond to a mouse click anywhere within its bounding rectangle, even if the sprite graphic itself only occupies a portion of this area. However, you can force Director to ignore the background areas of the sprite by using the matte ink effect, and in most cases this is the simplest way to create a button that's a non-standard shape.

However, the matte ink can cause undesirable fringing if the graphic has anti-aliased edges. In order to get around this, duplicate the castmember in question, and erase the antialiased edges from the copy, so there's a clean edge for the matte to work with. Then, place this cast on top of the other one on the stage, lining them up carefully. Give the proper castmember whatever ink effect looks right, and use the matte effect on your trimmed one. The trimmed one should be effectively invisible, and you can use it as your button.

(There are more sophisticated methods for defringing antialiased picts using image editing programs such as Adobe Photoshop if the results of this crude approach are unsatisfactory.)

If you want your matte button to be white, create the appropriate shape as a 1-bit bitmap, put it onstage with the matte ink and set the forecolor to 0 (either with Lingo or using the colour chips on the Tools palette). This should make it appear as a white shape with a transparent background.