I'm experiencing the same problem. I have a custom component (basic panel with a label) and it works fine as a custom tooltip for TextInput. But when using this custom tooltip has the tooltip for a TabNavigator child, the tab does not use the custom component. Instead a regular tooltip is shown with the text on the tooltip field.
Here is some code on the TabNavigator:
<mx:TabNavigator id="tab" toolTip="TT" toolTipCreate="createCustomTabToolTip('Tempos', tempos, event)">
<mx:VBox id="timeView" label="Tempos" toolTip="Tempos" >
Like I said the createCustomTabToolTip() function works, since when hovering over the VBox it shows the custom Tooltip. I just would like to know if it is possible for the TabNavigator to use that same custom Tooltip.
Thanks in advance.