i have an attempt at a SMIL animation of a simple SVG figure at http://jsfiddle.net/emanuensis/NNvjA/ The idea is that every mouseover the words up or down will cause the yellow puck to shuttle in that direction stoping a short ways, determined by the mouseout event ... and await further mouseovers, from that location.
Unfortunately the reality (in both FF & Chrome) is not so.
The form ABA (where A is any number of ups and B a down - or vv) results in a noop for the second A.
The first A freezes the value of the attribute at the first the value attained on the last event (there may be many always homeing anew) of its type (up or down). Ie the B starts (homes) from that position.
Even in the first A freezes are not additive. Ie every event homes before shuttling.
Perhaps there is another way of forcing an effective freeze for a short duration (ie not all the way to the end - which is a direction, not a magnitude.)
here da fiddly
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg id="svg2"
xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink"
width="400" height="500"
version="1.1">
<text id="tup" x="48 " y="33" >up </text>
<text id="tdn" x="235" y="33" >down</text>
<rect id="trect" style="fill:yellow;stroke:red;"
width="20" height="20" x="75" y="0" rx="5" ry="5" >
<animate id="tr"
begin="tdn.mouseover"
end="tdn.mouseout+1s"
attributeName="x"
additive="sum"
fill = "freeze"
restart = "whenNotActive"
from=""
to="50"
dur="3s"
repeatCount="1" />
<animate id="rt"
begin="tup.mouseover"
end="tup.mouseout+1s"
attributeName="x"
additive="sum"
fill = "freeze"
restart = "whenNotActive"
from=""
to="250"
dur="3s"
repeatCount="1"/>
</rect>
</svg>