Having this checkbox not checked (and not knowing about it) I had a problem to move at PCB elements I have just selected in the schematic. M moved block at schematic and not at PCB. Clicking at PCB unselected footprints (but not unselected symbols). I have asked how to move selected that way footprints. And I got info about that setting and also about P hotkey.
For me P is more fantastic than this focus following mouse (this can be bypassed by clicking PCB icon or at the top of PCB window). But of course it is better to not have to click.
Since V7 was released I had no time to carefully look through all menus and settings. For half a year I’ve been in a situation where I don’t know what to put my hands in.