The changes shown in this leaked screenshot of a Project NEON environment are subtle and admittedly pretty, but also potentially confusing. The biggest culprit will be the changes to the window borders, or rather the lack of those borders. Perhaps opting for a more unified look, the design has seemingly removed the visually distinct window title on top of the Groove, formerly “Groove Music”, app. The app name and window buttons have, instead, been incorporated into window itself, as if part of the window’s background. Gone also, is the usual visible border around windows.
While it does look less cluttered, it could pose some usability issues, particularly in terms of resizing and moving windows. Those bars and borders have always provided some visual cues as well as a convenient target when moving windows and especially when resizing them. While the functionality will most likely still be there, users might find it harder to discover it or even determine where they should grab the window edges.
Even more subtle is the color changes on the taskbar, which has seemingly been stripped of all color even for app icons. In a visual design sense, this means a more uniform look for the whole taskbar. It could, however, make it harder for some people distinguish icons at a glance, especially without text.
The one caveat to these changes is that nothing is official nor final yet. Microsoft has not made a peep about Project NEON, so there is little chance the changes will immediately be rolled out soon. It could be a good thing that screenshots like this get leaked, which could give Microsoft some early, but unsolicited, feedback even before the flip the switch.