The toggle All On/Off is already available for DFM Rules and every FAB3000 dialog box that has a column of check boxes (like Export, Layers table, etc.).
Move your mouse over the checkbox Column and Right-Click. All checkboxes will be toggled On/Off.
In this 10-sec video demonstrates right-clicking the mouse to toggle the entire checkbox column.
Simon Garrison
When I go to do DFM on our more complex boards it is beneficial time wise to only do one set of DFM's at once so it doesn't take so long to complete, and so the error list is much easier to deal with. I then disable all and switch to the next tab and enable all etc.
If you could add at the top of each of the 8 "DFM Checks" tabs an ALL-ON and an ALL-OFF button, that would speed configuration setup time.