File Group tabs jump around when clicking them???

strange behavior in WL:
sometimes (not always) when i click on a tab in the project window to select one of the files groups, that tab jumps to a different position in the order/sequence of the tabs. (not the tabs within the file group, but the tabs in the project)
quite annoying when there are lots of tabs and i have to find my orientation.

any idea?

thanks

Is this perhaps a case where the mouse cursor is sticking to the tab and causing it to move unintentionally when you move your mouse? It would be helpful to know what computer OS you are using and if you are surely using version 10.0.40.

Windows 10 64, latest WL
i suspected something similar. but the tab jumps not just 1 to the left or right, it jumps several tabs around.