change the image of a WebAsyncRefreshPanel's Progress Indicator

To change the WebAsyncRefreshPanel’s Progress Indicator image, you will need to handle the control’s client side InitializePanel event. In this event, you will then need to get a reference to the progress indicator itself using the WebAsyncRefreshPanel’s getProgressIndicator() method. Once you have a reference to the progress indicator, you can use its setImageUrl() method to change the image you want to use.

In JavaScript:

function WebRefreshPanel2_InitializePanel(oPanel)
{
oPanel.getProgressIndicator().setImageUrl("");
}