Unsolved Binding lost in component

[Tugdual]

Hi,
I'm trying to build an advanced component using QML that would be a date picker. It looks like a combobox that pops a Calendar instead of a list of item. I have created a date property which is bi-bidirectionally bound externally. The problem I have is that inside my component there is some script that updates the date property and as soon as I do that any biding is lost. So far I couldn't figure out how that component can change internally its value without breaking bindings. I also had a look on the spinbox which somehow affects its internal value with buttons but I can see here that C++ methods are used to change the value, not Java script.
Is it possible for a component to change one of its public properties without breaking external bindings?
Can anybody give me a clue on how to do that?
Help much appreciated.