User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.7) Gecko/2009021910 Firefox/3.0.7 (.NET CLR 3.5.30729) Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1b3) Gecko/20090305 Firefox/3.1b3 When the user moves the cursor over a drop target that overrides the dropEffect or effectAllowed values during the dragenter or dragover events, the cursor isn't updated to the corresponding values. Reproducible: Always Steps to Reproduce: Start a drag operation and during the dragstart event, set event.dataTransfer.effectAllowed = 'all'; During the dragenter and dragover events of a target element, set event.dataTransfer.dropEffect = 'copy'; or event.dataTransfer.effectAllowed = 'copy'; Actual Results: The cursor now shows the "move"-cursor unless you use a modifier key. Expected Results: The cursor should instead show the "copy" since the dropEffect or effectAllowed has been changed and the operation will be allowed to perform a drop. Whether or not the user should be able to change the dropEffect using modifier keys after it has been explicitly overridden is not the point here. It's the fact that the cursor doesn't correspond to the current operation that will be performed.

I have noticed the same problem on Firefox 3.5.5 on Mac OSX.