The first task SDBG will carry out is to save the running program's screen
display and replace it with the debugger screen, switching to text mode if
required. SDBG only displays information in text mode although you can debug
programs that use graphics modes supported by the Silverfrost graphics library.
SDBG makes use of a windowed interface. In common with other user interfaces a
mouse is not absolutely necessary but is extremely useful. The mouse cursor
will appear as a one character block in the middle of the screen.
The window that appears on top of all the others is called the current window.
The current window will respond to any key-presses or mouse actions. It can be
distinguished by the double line border surrounding the window. All other
windows have a single line border. You can change the current window by
pointing at another window and pressing and then releasing the left mouse
button. In this case the window you pointed to will be brought to the front and
you will see the border change.
You can cycle through the currently open windows by pressing Alt+N. The current
window can be moved by pointing to its title bar and pressing the left mouse
button. While the button is depressed you can 'drag' the window to its new
At the bottom right hand corner of a window you will see that the border thins
from a double line to a single line. The single line denotes the fact that you
can resize the window. This is achieved by moving the mouse to this area and
pressing and holding the left mouse button. You can then drag the window corner
to its new size.
At the top left corner of most windows you will see a box character (shown as
). By moving the mouse over this area and pressing the left mouse button the
window will close. You can also close a window by pressing Alt+F4. Some windows
will close when the Esc key is pressed.
When the SDBG screen initially appears it will contain three windows that sit on
top of the so called desktop window. Namely
a stack/status window,
a source code window,
a variables window.
If SDBG was invoked because of a run-time error, a description of the problem is
displayed in the stack/status window. Otherwise the stack/status window will
initially be hidden behind the source window which will show the current
execution point. Other windows called data view windows can be opened by
the user when required. These five differing types of window are described in
the following sections.