Oomox is a tool that allows generating color variations of the popular Numix GTK2 / GTK3 theme, as well as icons to match them.

The application comes with a large number of built-in presets that can be further customized, and it supports GNOME, Unity, Xfce4 and Openbox.

The minimum GTK3 version required to use it is 3.18 (so it supports Ubuntu 16.04 and newer). The themes might work with older GTK3 versions, but you may encounter issues.

Oomox already had Unity support, but with the latest 1.2.0 version, themes generated with it now have the correct window buttons color instead of the default Numix color:

Variety is a wallpaper changer that can automatically download wallpapers from various sources, like Flikr, Wallhaven, Bing Photo of the Day, Unslash, Desktoppr, NASA's Astronomy Picture of the Day, as well as a live wallpaper of the world sunlight map. It can also automatically fetch wallpapers recommended by other Variety users.

The app was updated recently with a new "safe mode" option, which can be used to avoid NSFW and sketchy images. This feature relies on user ratings, so it's not perfect, at least until more users rate the wallpapers.

Oomox is a tool that allows creating different color variations of the popular Numix GTK2/GTK3 theme. It features built-in presets, so you can easily generate various themes without much effort, or you can use the tool to change the theme colors individually.

In Ubuntu 15.10 (which uses GTK 3.16), there's a bug which causes some themes, like Numix, to have large black borders.

This bug only occurs for applications that use header bars (client-side decorations) and it affects Ubuntu (with Unity), while Xubuntu, Ubuntu MATE and Ubuntu GNOME don't seem to be affected (at least in my quick test). Update: MATE with Compiz enabled is also affected so I guess any desktop environment under which you use Compiz is affected (thanks to pawelp!).

Here's a screenshot with GNOME Clocks (an app that uses header bars) under Unity (Ubuntu 15.10), using Numix GTK theme:

For those not familiar with Gnome Pie, this is an application launcher inspired by a World of Warcraft addon called OPie.

The app consists of multiple "pies", each being triggered by a keyboard shortcut or mouse button you set. Each pie has its own role: applications, bookmarks, main menu, multimedia (play/pause/previous/next), a pie that allows you to control the focused window (maximize, close, etc.) and so on.

Folder Color is a file manager extension available for Nautilus, Nemo and Caja, which until recently could only be used to change individual folder colors. The tool was updated yesterday with a new feature: you can now use it to easily change all the folders colors with a click:

The default Ubuntu 15.04 Vivid Vervet wallpaper was revealed a few minutes ago. The wallpaper continues to use the polygon style introduced with the Ubuntu 14.04 default wallpaper, but without the orange. In fact, the new default wallpaper is mostly purple, as you can see below:

The winners of the Ubuntu 15.04 Vivid Vervet Community Wallpaper Contest were revealed yesterday. The new wallpapers didn't land in Vivid yet, but you can already download them via Launchpad.

Ideally, you'll need a complete GNOME 3.14 / 3.12 desktop to see what Paper is all about, since the theme uses custom colors for header bars / client-side decoration apps.