gtkIOStream is a set of C++ headers which enable you to make GTK GUI programs in a very trivial manner.
The nice thing about gtkIOStream is that they are only header files, this makes distribution easier, as you don't need to link against foreign libraries. As headers are inlined by the preprocessor, gtkiostream generates standard GTK C code at compile time. It is not strictly a C++ implementation of GTK, more a set of 'wrappers' around standard GTK C code which trivialises the generation of GTK GUIs. Because of inlining, the code resolves down to standard GTK C code by the preprocessor.
The following is the contents of the tutorials posted to the forums.
Tutorial 0 : Sets up prerequisites and introduces/tests that your compile system works.
Tutorial 1 : Explains the main program and shows you how to get an empty dialog up on the screen.
Tutorial 2 : Shows you how to load your first GUI widget into a GtkInterface dialog.
Tutorial 3 : Began to explain "packing" which is the way to layout your widgets in a desired manner in your dialog.
Tutorial 4 : Demonstrates how to layout widgets using a combination of horizontal and vertical packing boxes.
Tutorial 5 : Explains how to create buttons and callback functions. It implements the quit button to exit the gtk_main function.
Tutorial 6 : Demonstrates how to create GUI C++ classes, how to inherit and use of other GUI objects, and how to handle callbacks in C++ classes.
Hope that you get a lot out of these tutorials and you understand GTK GUI programming well from these tutorials.