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 location.
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.