I inadvertedly clicked the button "Problem is solved". That is not the case. I have gotten answers from iamjayakumars and Toad-Hall. Thanks, guys. So my question remains: Suddenly I can't move emails anymore in TB with the left mouse button from one submap to another. Meaning: make an email active; push the left button and hold it down; then drag the email to an other map. The dragging doesn't work. I tried several mouses. They all work well in other situations. With the mouse I can move program windows around the screen. Restarting the pc and reinstalling TB didn't help. As far as I can remember I didn't change anything in the options of TB. For the rest TB works as it is meant te do. See the other thread for already given answers.