Leopold said:
intriguing....lets' find out!
nope don't see that rule anywhere...where do you see that rule?
From the SRD, grapple section:
Grappling Consequences
While you’re grappling, your ability to attack others and defend yourself is limited.
No Threatened Squares: You don’t threaten any squares while grappling.
No Dexterity Bonus: You lose your Dexterity bonus to AC (if you have one) against opponents you aren’t grappling. (You can still use it against opponents you are grappling.)
No Movement: You can’t move normally while grappling. You may, however, make an opposed grapple check (see below) to move while grappling
Further from the SRD, in the Improved Grab section:
The creature has the option to conduct the grapple normally, or simply use the part of its body it used in the improved grab to hold the opponent. If it chooses to do the latter, it takes a –20 penalty on grapple checks, but is not considered grappled itself; the creature does not lose its Dexterity bonus to AC, still threatens an area, and can use its remaining attacks against other opponents
So, a normal monster without improved grab only has the option to initiate a normal grapple, and after which he doesn't threaten other areas, and has to continue any remaining attacks as per the grappling rules (grapple checks to do damage, -4 penalty to attack if he chooses not to do the grapple check, etc).
With improved grab, you get the free grapple check, and have 2 options.
Option 1 is to enter the grapple normally, with no penalty on the initial check, and be fully grappled (no dex bonus, no threatened area, etc).
Option 2 is to take a -20 on all grapple checks, and be able to continue attacking other opponents with your other attacks, move around freely, retain dex bonus, etc.
Skaros