The left and right side displays are exchanged and reread from the disk.
Because both sides are reread, unsaved edits would be lost. If a side carries any, Diffoniq therefore offers to save the modifications first; Cancel leaves the comparison exactly as it was and does not swap.
A read-only lock set for one side on the
command line
(/read-only-left or /read-only-right) travels with the
swap: the protected file stays protected in its new pane, and the title bar
follows. Without that, swapping would silently unlock a temporary file handed
over by another program.