Limit the scale to an specific value

[Javier Castillejo]

I 'm trying to limit the scale to 2000 (for example) and if someone try to
set another minor scale (<2000) i will set the scale to 2000

some thing like

if scale<200 then scale=2000

but

the extends change so the map seems to dessapear (extend from -
450000.000000 3817875.000000 1100000.000000 4982125.000000 TO -142.111035 -
106.833276 140.111035 104.833276)

I'm using jbox to pan, drag and zoom but jbox doesn't do what it's expected
to do

thanks