PHP中的回发

Is there a way to check which link/button was clicked from a form besides using

if(isset($_POST['myvar']))
{
//if true do this
}
else
{//do this}

or a querystring?

My page has a jquery drop down and thus the above isset function is not working as the form for login is contained in the dropdown.

I'm not too familiar with PHP, but going the jQuery route, you can create a hidden field

<input type="hidden" name="postSource" id="postSource" />

and then wire up some event handlers to modify that value before the page is posted.

$('#myControl1, #myControl2').change(function()
{
    $('#postSource').val($(this).attr('id'))
});

.NET uses a similar technique, I think. Then on server side, you just access the posted value of the 'postSource' field.