dynamic layer filter, again

[Mauricio Stange H.]

Hi, me again,
    please, does somebody know, how to do this. I already have posted 
the question.
    Since then I tried with every time recreating a mapfile, (reading 
from a map file without the filter and inserting it in the new file), 
but I have problems with it, sometimes I select another filter and the 
map does't change unless I use a map control.
    I tried with mapscript too: got the map, got the layer, and have set 
the filter property, but how update the modified layer into the map???

Please, if somebody have an idea....

Thanks,
    Mauricio Stange H.