[doc] added docstring to on-mousemotion

1 files changed, 13 insertions, 0 deletions

diff --git a/src/events/event-handler.lisp b/src/events/event-handler.lisp
index bd40849..b8c72ef 100644
--- a/src/events/event-handler.lisp
+++ b/src/events/event-handler.lisp
@@ -78,6 +78,19 @@ can be redefined using this form to support interactive development."
                         ,@body)))
 
 (defmacro on-mousemotion
+    "ON-MOUSEMOTION defines a mouse motion event handler.  All
+variable arguments supplied the the ON-MOUSEDOWN handler form are
+optional. You may supply your own variables to use in your BODY or you
+may just refer to the defaults - they will be interned in the
+appropriate package.
+
+- TARGET is the object ontowhich the handler was installed
+- X and Y are the scaled screen coordinates 
+- XREL and YREL are the relative motion of the X and Y positions since
+  the last event, in scaled coordinates
+- STATE is the button state, see the SDL2 docs
+- WIN-* variables are the unscaled event values, if you require them.
+"
     ((&optional
         (target 'target)
         (x 'x) (y 'y)