Pgadmin data output string disappear when reach 3278 length

- Ver 1.16.0(Sep 7 2012; rev REL-1_16_0)
- Windows XP Pro, SP3

- Steps required to reproduce the problem:

Execute
select array_agg('M'::TEXT)
from (select generate_series(1,1637)) as atable;

So we get string {M,M ... ,M} *3276 *length. It's correctly displaying at
data output pane.

Execute
select array_agg('M'::TEXT)
from (select generate_series(1,1638)) as atable;
Data output is empty. But if we will copy value from data output and paste
it anywhere else, we will get string {M,M ... ,M} *3278 *length.

Is it a bug or a known restriction?

P.S: sorry for poor English.