Blinking on bottom window list area on Peppermint One 01042011

Mozila Firefox always blinking in bottom window list area. I don't know why it is blinking. I thought Firefox is not in-front of other window. I select some text on a website, scrolling dragging by mouse. That little space for Firefox at bottom window list area is still blinking. (Blinking= goes bright and dark continuously.) I am going to post it in PeppermintOS forum very soon.