You can increase the [nudge] Down=# value in iGMap.ini. This will do what you want, but it will always be like that. I was planning on allowing all INI settings to be changable at run-time via script commands, but I never really did that

.
...so to do what you want I would have to add a command like this:
NudgeDown([Window]:[Value]).
Then you could set a button down to NudgeDown(iGMap:80) and button up to NudgeDown(iGMap:20) to toggle info-bar on/off.
(Unfortunatly that command does not yet exist

)