First defined in: FKiSS3
The letmousex action sets the value of variable to the
current horizontal position of the mouse pointer. This position is
relative to the play field and might be negative.
This value may be outside the edges of the play field, viewport, or
window. Note that on some operating systems, it is not possible for the
KiSS viewer to know the location of the mouse when it is outside of the
viewer window. In that case, this value will represent the position of the
mouse at the last moment when it was inside the viewer window.
variable
variable must be a variable name.
Example:
;@ letmouseX(X) ; Set variable X to the mouse pointer's horizontal position.