Dialog creation setting colors

Introduction
This is an example of dialog creation with PySide.

In this example, the entire interface is defined in Python. Although this is possible for small interfaces, for larger interfaces the recommendation is to create files through Qt Designer, and load these in the program. See Interface creation with UI files.

Use QColorDialog to get a color
Complete code:

Use QColorDialog to create a palette of colors (standard and custom)
This example modify the Standard color and the Customize color with the Tango FreeCAD guide.