Unexpected params in URL line

We have some CSS magic that we are using to hide or show the left bar in our Foswiki pages. (Yes, we could use JavaScript; I'm not a JS expert; CSS is working; thanks).

It works.

My question is, why am I getting two extra URL params that I'm not (explicitly) sending? I've used HTML forms in other laces in FW and this is the first time I've seen unexpected URL params.

The code (http://wiki.cfcl.com/System/WebTopBar):

<table border="0" cellpadding="0" cellspacing="0" style="width:100%" summary="">
<tr><td valign="top"><form name="hideshow" action="%SCRIPTURLPATH{"view"}%/%INCLUDINGWEB%/%INCLUDINGTOPIC%" method="get">
&nbsp;
<input type="image" src="%PUBURL%/%USERSWEB%/DocumentGraphics/%IF{ "$leftbar~'*Hide*'" then="showleftbar.png" else="hideleftbar.png" }%" title="%IF{ "$leftbar~'*Hide*'" then="Show Left Bar" else="Hide Left Bar" }%" name="leftbar" value="%IF{ "$leftbar~'*Hide*'" then="Show" else="Hide" }%" />
</form></td><td valign="middle"> <span id="foswikiLogo" class="foswikiImage"><a href="%WEBLOGOURL%"><img src="%WEBLOGOIMG%" border="0" alt="%WEBLOGOALT%" style="border:none;" /></a></span></td>
<td align="right" valign="top" class="patternMetaMenu">
%IF{ "$leftbar~'*Hide*'" then="<link rel='stylesheet' type='text/css' href='%PUBURL%/Help/HideWebLeftBar/noleftbar.css'>" else="<link rel='stylesheet' type='text/css' href='%PUBURL%/Help/ShowWebLeftBar/showleftbar.css'>" }%
<noautolink>%INCLUDE{"%IF{"context can_login" then="%SYSTEMWEB%.WebTopBarLogin" else="<nop>"}%" warn="off"}%
</noautolink></td></tr></table>

The URL line that I see:

http://wiki.cfcl.com/Web/Topic?leftbar.x=28&leftbar.y=8&leftbar=Hide

I don't understand why I'm getting leftbar.x and leftbar.y.

-- VickiBrown - 14 Apr 2014

Basic HTML. http://www.htmlhelp.com/reference/html40/forms/input.html "When the graphical submit button is clicked, the coordinates of the click are sent with the form submission as name.x=x-value and name.y=y-value where name is the value of the NAME attribute, x-value is the click's pixels from the left of the image, and y-value is the click's pixels from the top of the image."

-- CrawfordCurrie - 14 Apr 2014