* OVERVIEW

After starting, GTKMathplot shows a window with a menubar and two "pages"
with only one page visible, namely the Input page.

The Input page contains essentially an input mask, 
other than a couple of buttons and a combo.
In the mask you should enter the information related to the objects
you want to display, in particular the associated cartesian/parametric 
equations. In other words, the input mask should be used to define the
objects that have to be visualized.

The other page, i.e. the Output page, consists mainly of a "canvas" where to
draw the mathematical objects and of some controllers.
These ones can be used to adjust or change the parameters and the attributes
which determine how the objects are exactly drawn.
The Output page is initially hidden, and you can display it by clicking
on the page indicator (page indicators are also known as tabs) with the
label "Output".
Whenever I say "click", here and in the following, I mean clicking with the
left button of the mouse unless otherwise specified.

If you click on the "Output" tab, the Output page arises and shows
a completely white canvas: since you have not entered any mathematical
equation yet, there is no object to visualize.
To move back to the Input page, you should either click on the "Input"
tab or on the button "Back to input mask".

After entering in the Input page the description of one or more
mathematical objects, you can visualize them by clicking on the
button labeled with "Display/Update graphic". 
If you click on this button before defining any mathematical object, 
or after clearing all previously entered definitions, 
then nothing will be shown in the canvas.

The Input page provides the button "Quit", click on it 
to terminate the program. You can also terminate the program by
clicking on the entry "Quit" from the "Main" menu in the menubar,
or by pressing the key 'q' while holding down the Control key
(this is the shortcut Ctrl+Q).

In the menubar you can also see the "Edit" menu.
This one provides the entry "Preferences". If you click on it,
then the "Preferences" window appears, where you can change some settings 
(like colors, symbols, paper format) which are used while drawing the
mathematical shapes on the canvas or while exporting them to a 
Postscript/PDF file.

The menubar provides also a "Help" menu.
The "Help" menu has the entries "Help", "License", and "About".
Click on "License" to get a short notice about the distribution terms
of GTKMathplot, on "About" to get copyright statement and email
address of the author.

If you click on the entry "Help", a window is shown containing this
help text. You can display the help text also by pressing the key 'h'
while holding down the Control key (this is the shortcut Ctrl+H).

** NAVIGATION AND EDITING

You can navigate through the elements of the graphic interface
of GTKMathplot using the Tab key. Whenever you press the Tab key,
the focus moves to the next element (an entry, a button,
a combo) of the interface. If the focused element is a button or a combo,
pressing the Enter key has the same effect as clicking on it.
If the focused element is a group of radio buttons,
you can use the arrow keys to change the selected button; care that
Up-arrow and Left-arrow key move the selection in the same direction,
just like Down-key and Right-key do.
In case the focused element is a slider, you can employ the arrow keys
to change the associated value: Up-arrow and Left-arrow decrease the value,
Down-key and Right-key increase it.
If the focused element is an adjuster, you can increase the associated
value by pressing the Up-arrow key, and decrease it by pressing the
Down-arrow key.
Finally, if the focused element is a text entry, then you can employ all
usual keys to move along it (Home and End key, in addition to the arrow keys:
they all work as expected), you can erase the character under the cursor
by pressing Del(ete), and the character before the cursor by pressing the
Backspace (<--) key.
If you want to select the text contained in an entry or part of it, then
you should hold the Shift key down, either the left or the right Shift key,
while pressing one of the arrow keys, or the Home key, or the End key.

Once the last element of the currently active page or window has been reached,
a further pressing of the Tab key moves back to the element which was
focused as first: the navigation with the Tab key is cyclic.
If you want to navigate in the direction opposite to the one of the Tab key,
you should hold the Shift key down while pressing Tab (this is the shortcut
Shift+Tab). The navigation with Shift+Tab is also cyclic.

** GENERAL SHORTCUTS

- Ctrl+q : Quit GTKMathplot
- Ctrl+h : Show the online help
- Ctrl+p : Open the "Preferences" dialog window
- Ctrl+a : Open a dialog with copyright information

- Alt+m  : Open the "Main" menu
- Alt+e  : Open the "Edit" menu
- Alt+h  : Open the "Help" menu
- Esc    : close a menu or dialog window

REMARKS 

- Ctrl+key   is the combination obtained by holding the Control key down
             while pressing `key',
- Alt+key    is the combination obtained by holding the Alt key down
             while pressing `key',
- Shift+key  is the combination obtained by holding the Shift key down
             while pressing `key',
- Esc        is the Escape key.
