Apps to Built-in themes

Kontact is a comprehensive personal information management suite from KDE combining email, contacts, calendar, tasks, and news in one integrated application. It offers robust synchronization options and supports various protocols.

Rambox is a FOSS and portable messaging and emailing application that consolidates numerous web services into a single, convenient interface. It supports a wide array of communication and collaboration platforms, including popular chat, email, and social media services, offering a unified experience with features like unified inbox and notifications.

Scribes is a free and open-source minimalist text editor designed for programmers and writers who value simplicity and efficiency. It provides a clean interface with essential features like syntax highlighting, autocompletion, and extensibility through plugins, making it a lightweight yet powerful tool for various coding and writing tasks.

Textadept is a powerful, free, and open-source text editor designed for programmers. Focusing on speed and extensibility, it offers a minimalist interface while providing robust features like syntax highlighting, code formatting, and a built-in terminal, all heavily customizable through Lua scripting.

Robomongo, also known as Robo 3T, is a free and open-source cross-platform GUI tool for MongoDB. It's a lightweight and intuitive database management application that directly embeds the MongoDB shell.

Kate, the KDE Advanced Text Editor, is a powerful yet lightweight text editor popular among developers and advanced users. Offering robust features like syntax highlighting, built-in terminal, extensibility via plugins, and comprehensive customization options, Kate caters to a wide range of text editing and coding tasks across platforms.

Digsby was a multi-protocol instant messaging client that unified connections to various chat networks and social media platforms. It allowed users to manage their conversations and updates from services like Aim, Msn, Yahoo, Twitter, Facebook, and Myspace all within a single, integrated application.

GNU Emacs is a highly extensible and customizable text editor, renowed for its powerful features and ability to serve as a complete development environment. It is based on the Emacs Lisp programming language, allowing for deep customization and a vast ecosystem of packages.