Trackball drag

KensigntonWorks (software for Kensington) has an option to assign buttons to OS functions. One that worked in the past but I can't get to work correctly now is "Drag". It should let you click on an object and drag it without holding the mouse button down. For example drag a window around the desk top. It will usually work now by double clicking the designated trackball button but it should work with a single click. Kensington claims it's a MacOS bug. Apple claims its a Kensington bug.