loading widget

Hello all,

In the application I am working on, I see some inconsistencies in the appearance of the loading sign. 
I am using a  combo box, with an onchange action which executes a query (the results will be shown in a tablerecords widget).
When selecting an option of the combobox, the onchange is fired and a 'loading'' sign should show up in the bottom left of the page. This works fine sometimes, but at other times the widget only shows for a brief period of time or not at all.
Can anyone tell me the criteria for this widget to be shown (when is it triggered and for how long)?

Hi Martha,

I don't know the threshold but the message only appears if the ajax request takes "too long".

In this situation it seems to be the case though that the loading sign appears and disappears even before the (heavy) query is being executed, so in the midst of the ajax request..