How to set the BC just one instance?

[woshichuanqilz]

I wonder is there a para to in the command line to make the `new comparison` open in a new tab instead of start another BC instance?

[Chris]

Beyond Compare 4 doesn't provide a command line switch to open a new comparison in a new tab vs a new window.

To control tab vs window behavior, open Tools > Options.
Go to the Tabs section.
For the settings Open sessions in and Open child sessions in, select A new window or A new tab.