Windows 3.1 Device Drivers (ddag31qh.hlp) (Table of Contents; Topic list)
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Mouse Trails
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In Windows 3.1, display drivers can improve mouse cursor visibility
(especially on liquid crystal displays (LCD)) by supporting mouse trails. A
mouse trail is a sequence of two or more cursor images that mark current and
previous mouse cursor positions. A display driver creates a mouse trail by
drawing a cursor at each new mouse position and leaving additional cursors
at previous positions. The driver delays erasing the previous cursors until
a specified number of cursors are visible.
 
A display driver provides support for mouse trails by processing the
MOUSETRAILS escape in its Control function. The MOUSETRAILS escape enables
or disables mouse trails. It also sets the maximum number of cursors to be
displayed in the trail. The display driver must also process the
QUERYESCSUPPORT escape, returning the status of the mouse trails if the
requested escape is MOUSETRAILS.
 
The display driver draws the mouse trail when it processes the MoveCursor
function. Any trailing cursors must have the same shape as the current
cursor. The display driver should provide mouse trails for system cursors,
such as the pointer and hourglass, and for application-specific cursors as
well. Currently, support is not provided for mouse trails for XOR-only
cursors, such as the I-beam and the cross-hair cursor used by PaintBrush.
 
The display driver is responsible for recording the mouse trail status by
maintaining the MouseTrails setting in the [Windows] section of the WIN.INI
file. The driver switches this setting to a positive value to indicate that
mouse trails capability is enabled. The value also specifies the number of
cursors to display. The driver switches this setting to a zero or a negative
value when mouse trails capability is disabled. The absolute value specifies
the number of cursors to display prior to being disabled.
 
Users can turn mouse trails on or off by using Windows 3.1 Control Panel.
The mouse settings dialog box displays a Mouse Trails option.
 
Applications should not enable or disable mouse trails. However, third-party
mouse configuration programs should.
 
 
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