On only one of my computers I’ve a white rectangle in WunderMap® | Interactive Weather Map and Radar | Weather Underground. It started with FF3.6x. I’ve upgraded to FF8x and then FF9x. I’ve updated and run Malwarebytes, Ad-Aware and Avast. I can drag the white rectangle and the map around it in all directions is OK until I release the left click on the mouse and then the white rectangle moves to the new location on the map.
IE on this computer and FF and IE on my other computer do not manifest this problem.
I’ve the creepy feeling that I have asked about this before but cannot find any previous thread.
Conjectures? What should I try next?