GTK+ is a highly usable, feature rich toolkit for creating graphical user interfaces which boasts cross platform compatibility and an easy to use API. GTK+ it is written in C, but has bindings to many other popular programming languages such as C++, Python and C# among others. GTK+ is licensed under the GNU LGPL 2.1 allowing development of both free and proprietary software with GTK+ without any license fees or royalties. [Source: gtk.org]
As GTK+ is a graphical library, a program using GTK+ can be done in many languages like C, C++, Python, Perl, PHP, Ruby, and many others. Here a C example will be done.
How to make a simple program with GTK
An easier way to make a graphical interface (GUI) program using GTK+ is to use Glade as Graphical Editor.
To install Glade on Ubuntu type:
$sudo apt-get install glade-3
Old Glade versions used to generate C code. Currently version ONLY generates a .glade file that can be parsed in a .xml file which describes the hierachy of the widgets.
Let's create, compile and test a sample program on host and after, cross-compile for iMX platform and check it running on a PDK i.MX31 Development kit.
In order to develop on host PC, install libgtk2.0-dev typing:
$sudo apt-get install libgtk2.0-dev