Changing the Appearance of Scroll Bars

Vermont Views scroll bars are similar in appearance to those of Microsoft Windows and the Macintosh. They differ in some ways from the IBM CUA specifications for scroll bars. If you want to change the way the scroll bars appear and how they are updated, the following functions can be rewritten and replaced in the library:

int wn_sbdraw(wnp)

WINDOWPTR wnp;



int wn_sbupd(oldpos, newpos, sb_type, wnp)

int oldpos;

int newpos;

ULONG sb_type;

WINDOWPTR wnp;

wn_sbdraw() draws the scroll bar(s) on the window border and then calls the scroll bar update function wn_sbupd(). wn_sbupd() removes the thumb from its existing position on the scroll bar (oldpos) and places the thumb at its new position (newpos).

The only special rule that applies to writing these functions is that if wn_sbupd() is passed -1 for the old position, it should not remove the thumb character from where it currently is placed.

In addition, if the scroll bar cover size is not 4, you must also inform the system that the size of the cover has changed with:

se_sbcoversize(size)

int size;

where size is the number of characters not used by the page region on the border. The cover size should be the same for both horizontal and vertical scroll bars.