With Android 3.0 Honeycomb, came along the lack of a menu button on devices. In Android 4.0 Ice Cream Sandwich, no hardware button means that developers need not map it in their applications anymore.

Before Honeycomb, the button was used for applications to deliver various options that were relevant to the user, using the activity’s built-in options menu.

Since the physical buttons were removed in Android 3.0, the ActionBar class came to the stage to make options immediately visible to the user. Ice Cream Sandwich follows on the same tradition, and applications built for the new OS flavor need to change to come in line with the new requirement.

“In order to provide the most intuitive and consistent user experience in your apps, you should migrate your designs away from using the Menu button and toward using the action bar,” Scott Main, lead tech writer for developer.android.com, explains.

“This isn’t a new concept — the action bar pattern has been around on Android even before Honeycomb — but as Ice Cream Sandwich rolls out to more devices, it’s important that you begin to migrate your designs to the action bar in order to promote a consistent Android user experience.”

For developers looking to offer support for devices running under pre-Honeycomb OS flavors as well, things should be pretty simple. They will need to add support for the action bar on newer devices, while keeping the Menu button on older ones.

Moreover, Scott Main notes that devs should “stop thinking about activities using a ‘menu button’,” in addition to no longer relying on the hardware Menu button for their applications.

“Even if your app is built to support versions of Android older than 3.0 (in which apps traditionally use the options menu panel to display user options/actions), when it runs on Android 3.0 and beyond, there’s no Menu button,” he notes.

“The button that appears in the system/navigation bar represents the action overflow for legacy apps, which reveals actions and user options that have ‘overflowed off the screen’.”

App builders interested in learning some more details on this should have a look at this post on the Android Developers blog.