I have carefully read the examples you provided here and this one in particular seems to be the one I need
[C#] Example 4: A custom FilterDescriptor
// Give me all people that are with first name John.
var fd =
fd.Operator = FilterOperator.IsEqualTo;
// In most cases the data engine will discover this automatically so you do not need to set it.
It works. The grid starts filtered as expected, however it is not possible for the user to revert that initial filter.
Is there anything missing? I tried to find a running example for those filterdescriptors, but i couldn't. If there is one, can you please provide it?