filter on a form - how?

[paucer]

I need add some functionality to a form, but only when filtering is enabled.
How can i check this?
Form's datasource has mathod filter(), but it seems this method isn't invoked, when user press filter shortcut button or press CTRL+F3 or filter from context menu. I tried to use prompt() method, but it isn't invoked when filtering is started via context menu. And i need do additional calculation, when the filter is enabled or is being disabled - removeFilter() works ok.
So how can I manage filtering?
At least i must know if fitering is turned on or off.

[rumpleteazer]

To intercept pressing of filter button, you should use task-method on a form. The input parameter for this method is task-event id. Filter event id is 2837, but you should better use macro Task (#taskFilter).

Example:

public int task(int _p1)
{
#Task
int ret;

if(_p1 == #taskFilter)
{
// you code handling filter-event goes here
}
ret = super(_p1);

Return ret;
}