terms.txt

color			we can color objects: fill the inside of an object or specify its lines' colors;
				and we can color individual pixels. pixels use the RGB scale to represent colors
				from values 0 to 255 for each channel: red, green and blue (and optionally alpha)
				we can enter rgb values using decimal numbers rgb(123,0,255) or hexadecimal numbers
				(#FFAB01; where FF is the red, AB is the green, and 01 is the red channel)
graphic			two-dimensional data representation on a screen, or in a window, coordinates specify
				their pixels, we can create objects of graphical types that the display engine
				can handle and represent graphically, using individual pixels
JPEG			file format that can represent pictures using pixel information
coordinates		windows and screens require coordinates to address their pixels
				the (0;0) point is on the top-left, x-coordinates increase to the right,
				y-coordinates increase downwards
GUI				Graphical User Interface: support for input and output using graphical elements,
				such as windows, text, images, shapes, buttons and other input fields
				the communication channel between the user and the program
line style		we can modify a shape's lines' or a line's style from a plain line to dashed,
	 			dotted and change their thickness and color
display			a window or a screen that presents information for its users
PPP_graphics	our GUI library
library			a set of useful general-purpose functions, classes that we can use, that are
				usually well-made, well-tested and well-documented, something that we can't
				afford to do for our smaller projects
software layer	a layer of abstraction for code inside our programs
fill			we can fill shapes with a color
Shape			a class type that we can use for shapes (Line, Polygon, Rectangle, etc.),
				Polygon is a Shape
HTML			layout language: we can express layout notions in plain text, but needs a parser
				to interpret the notions. we can embed notions of color, two dimensional-positions
				in a one-dimensional stream of characters
window			a virtual screen on our physical screen that is managed by some program
Qt				Graphics / GUI library that provides portable, platform-independent graphics for its users
image			usually a file that contains per-pixel information for an image
XML				layout language, similar to HTML
Simple_window	class in our GUI library that provides an easy-to-use window with a button
				with the label 'Next' on it