Quickly is a great little tool for producing and packaging Ubuntu (PyGTK) GUI applications - quickly. It takes out most of the manual, repeating work involved, so that you can entirely focus on your application's functionality instead of setup details.
The Qt Software Development Kit (SDK) is a cross-platform application framework that is widely used for developing application software with a graphical user interface (GUI).
How to Install Qt SDK on Ubuntu Linux
Here is a list of handy open source development tools for use on Ubuntu such as Integrated Development Environments (IDEs) and powerful editors.
Anjuta is an Integrated Development Environment (IDE) for C and C++.
Bazaar-NG is a decentralised version control system used for Ubuntu development.
Bluefish is a powerful editor for experienced web designers and programmers.
Eclipse is an IDE for Java and other programming languages. It forms the basis for closed-source programs such as JBuilder.
Eric is a fully featured Python and Ruby IDE.
Glade is a User Interface designer for building GNOME applications.
IDLE is the Python IDE built with the Tkinter GUI toolkit.
KDevelop is a IDE for KDE which supports many programming languages.
MonoDevelop is an IDE for writing mono/.net applications in C# and other languages.
NetBeans is a Java IDE that features support for CVS and a form builder.
Other resources that you can use:
Ubuntu App Developers
Ubuntu Developer’s Manual
Ubuntu Development Guide: Introduction
Ubuntu's single platform SDK to be ship shape by October
The Ubuntu SDK that will allow developers to build apps that can run across phones, tablets and desktop PCs should be mature enough to build most applications by October this year.
When it is complete the Ubuntu SDK, released in Alpha earlier this year, will allow developers to use the same code base to create apps that run on Ubuntu across multiple form factors. It ties in with the plans by Canonical, the organisation which develops Ubuntu with the community, for Ubuntu to be a single OS that runs across phones, tablets and desktops.
Canonical is aiming for the SDK to be complete enough for most applications to be written by the time Ubuntu 13.10 is released.Zdnet