Opening defined tab using @tab_idx not supported for --openjmx

[jisedlac]

VisualVM 2.1.

The --openjmx command line option doesn't support opening the process view at a defined tab, as already available for --openid <id@tab_idx> and --openpid <pid@tab_idx>.

Would be nice to have this functionality available also for --openjmx <host:port@tab_idx>.