see the panel generate html
<div id="yourPanelClientID" onkeypress="javascript:return WebForm_FireDefaultButton(event, 'btnSearch')">
so, when btnReset onfocus we break onkeypress event of Panel, add below to btnReset, remember when btnReset onblur, change Panel keypress to oringinal
onfocus="document.getElementById('yourPanelClientID').onkeypress = '';"
onblur="funA();"
function funA() {
document.getElementById('yourPanelClientID').onkeypress = function () { return WebForm_FireDefaultButton(event, "btnSearch") };
}
like this
<asp:Button ID="btnReset"
onfocus="document.getElementById('yourPanelClientID').onkeypress = '';"
onblur="funA();"
onclick="btnReset_Click" .../>