The Scroll Bars

Presence

The vertical scroll bar is shown whenever the value of `rows is less than the number of rows in the array, and the horizontal scroll bar whenever `cols is less than the number of columns in the array.

Function

Each scrollbar performs several functions.  The display is moved one row or column by clicking the left mouse button on an arrowhead at an end.  The display is scrolled, with an overlap of one row or column, by clicking the left mouse button in the channel but not on the elevator.  It snaps to a new position when the middle mouse button is pressed anywhere in the scrollbar.  It is dragged by pressing the middle mouse button anywhere on the scrollbar or the left button anywhere except on the arrow heads, and then moving the pointer.

When the right mouse button is pressed on a scrollbar a menu appears, with the choices Openlook, Motif (the default of these two, of course), Home, and End, all for that bar only, naturally.

Size

The depth of the horizontal scroll bar is `hscrollsize and the width of the vertical `vscrollsize (the default for each is 15).  The `scrollsize attribute controls them both, and can be a scalar or one or two element vector;  when its length is two, it is equal to `vscrollsize,`hscrollsize.

Color

The background of both scrollbars is the value of `scrollbg, or if it is null, the value of `bg, or if it is null, grey and dark grey.  The darkening of the channel is not maintained when the scrollbar background is set, but if the user changes the scrollbar to Openlook and back to Motif, using the scrollbar menu, the darkening of the channel reappears.  At present, if `bg is set to a new color after `scrollbg is set, the latter is reset to the new background color.

The foreground is controlled by the window manager.

When both scroll bars are present, there is a rectangle at the bottom right where they would overlap if extended.  This area is not really part of the scrollbars and is unaffected by the setting of `scrollbg.