
 Title: Mode22
 Author: Tim Dobson
 History:
        05-Dec-91 TMD Created

From RISC OS 3.03 onwards a new screen mode (22) is available, on monitor
types 0 and 1 only, which is suitable for use by visually impaired people.

In terms of pixels and colours the mode is equivalent to mode 35 (an
overscan mode), ie 16 colours, 768 pixels by 288 rows.

However, the ratio of OS coordinates to pixels is changed so that instead of
the screen being 1536 by 1152 coordinates like mode 35, it is only 768 by
576 coordinates. This results in most text and graphics in the desktop being
drawn twice as large in both X and Y directions, thus making them easier to
see.

There are currently a number of problems associated with this mode:-

 a) The desktop tool sprites (ie the sprites used in window borders and the
like) are inappropriate for this mode, causing some horizontal lines to
become double thickness, and some vertical lines to disappear entirely.

 b) Some applications (including those in the ROM) create windows of a
certain size without scroll bars, and assume that the screen will be big
enough in one or both directions to accommodate the whole of the window.
Some parts of these windows may then be inaccessible.

 Examples of this are:-

 Filer windows with 'Full info' selected
 !Alarm 'Setup','Set clock', 'Set alarm' (particularly repeating alarms)
   windows
 !Chars window
 !Draw toolbox (goes partly off bottom)
 !Edit 'Find text' window (particularly with 'Magic characters' or
   'Wildcarded expressions' turned on


 c) Some applications may create windows and then assume that the
window has been created that size, and then create icons in that
window assuming that size. The icons will then appear in the wrong
place, eg overlapping other icons.

 Examples of this are:-

 !Paint tool window with various tools selected (eg use sprite as brush)

 d) Some applications may create windows aligned with the bottom of the
screen, such that the title bar goes completely off the top of the screen.
The window therefore cannot be moved.

 Examples of this are:-

 Some !Impression windows.

 e) Some applications which use sprites to update their windows, always use
a fixed number of pixels for their windows. The inside of the window
therefore does not appear double size.

 Examples of this are:-

 PC emulator (in a window).
