ask file with filter/type - how to read the selected type ?

[viktoras didziulis]

is there any way to know what file type user selects in ask file with 
filter dialog ? I need to specify different handlers for file "Save as", 
and now am first asking user to select the type of a desired output 
(i.e. raw binary, ascii text, png image or ppm image) and next opening 
ask file dialog to get the path for saving the data. But I know "this is 
not good", because users are used to a single dialog for file saving 
where they choose save as type and the data is processed without any 
additional disturbances... The problem is that the selection of ask file 
dialog is returned in 'it' variable but the selected type of file in the 
dropdown list of that dialog is not returned in any readable way, or is 
it?..

Best regards
Viktoras