@semi55 I think the best solution would be to hide the U axis all the time. I'm checking with @dc42 if there's a bug in this part, or a workaround. Hiding U is the best option; then only one tool will move at a time using the X jog controls, and when the tool is deselected, use tree#.g to send it to its home position, so the other tool can't reach it.
The other option would be for DWC to send M400 after the jog command, if the U axis is jogged instead of X when tool 1 is selected. But this may cause stuttering if the jog button is pressed multiple times, as M400 would cause the axis to stop after each command.
Anything else will be a support problem for you, and prone to user error (eg selecting wrong machine configuration when slicing) especially having to set up a slicer with custom codes to configure the tools.
Ian