The fourth Developer Preview of Android O ships with a number of changes, many of which are now being discovered by users as Google has yet to officially detail them, with one of them being a slightly redesigned Lock Screen interface. As seen in the gallery below, the date shown on the Lock Screen now isn't written exclusively in uppercase letters, whereas the size of the clock icon was reduced, seemingly so that its width corresponds to the width of the date. The message on the top of the screen that appears when you boot a device without a SIM card was also modified to a degree, with the new warning telling you that the smartphone can now only be used for emergency calls instead of presenting you with a more generic "no service" message, though Google has yet to clarify on whether this particular feature is now the default message in the fourth Developer Preview of Android O or if it's still triggered by certain conditions seeing how the same warning was also sighted in older builds of the operating system, though users were previously unable to find a reliable method of triggering it.
That same message can also be seen once you pull down the notification panel, though it's gravitating toward the center of the screen, and the same goes for the time icon in the top-right corner of the interface that's now a bit closer to the left than it was in previous experimental builds of Google's next OS. While all of the aforementioned changes are minor, they still add up, resulting in a design that's somewhat more symmetric than the one seen in the previous Developer Preview of Android O. One final change seen in the last version of Android O pertains to the date shown on the notification panel that's now seemingly using a wider font with more spaced out letters.
The Mountain View, California-based tech giant recently confirmed that the fourth Developer Preview of Android O will also be its final one before the OS hits the stable channel later this summer, presumably by the end of August. The Google Pixel, Pixel XL, and a number of models from the Nexus series will be the first to receive the Android O update before the next major iteration of the OS rolls out to third-party devices later this year.