Automatic data binding mysteries

[master_tz]

I have some questions about how and when data sources are bound in the page lifecycle, and I can't seem to find the answers anywhere.I have a gridview which is bound to a data source at design time. One of the parameters for the DS is the selected value of a dropdown list. These dropdown lists are also databound to retreive their options, and the dropdowns have their auto-postback property set true. Now some things are confusing me about this.[*]Most of the time changing the value of the dropdown will reload the gridview with the new parameter, and it's not necessary to manually call databind() on the gridview in order to do so. However there are situations where the gridview is not rebound, and I'm not sure what these conditions are. When will a data-source be rebound automatically upon parameter change, and when do you need to call databind manually from code?[*]Does calling databind from codebehind prevent the automatic databind event from firing, or will they both fire, resulting in a wasteful extra query of the data source?[*]If the former, is there a way to stop the extra databind from occurring without having to move everything into code behind and lose the convenience of setting up data sources for the controls in the design view?[*]Are the answers to these questions documented on any official sources? (MSDN, etc)