InstallAware

I needt to perform some action on change of a ComboBox/ListBox (e.g. reload the dialog box) ... something similar to JavaScript's onChange-Event? How to do this?

I'm not sure what you mean by "reload the dialog box".

Nevertheless, InstallAware doesn't provide event-driven processing.

What you would probably want to do is something like this:

On the first form with the combobox, make the user make the selection they want.
They have to click button "continue" or "next" after making that selection.

The next form displays and based on the selection in the combobox on the previous dialog, you can display that selection and the associated options with it on the next form.

If they didn't like that selection, they can click a button to go back to the previous dialog to edit their combobox selection.

OK, i will come a little bit closer to my problem: I have a custom dialog to select the setup language. Languages are listed in a ComboBox. When the user select the setup language, the dialog should immediately/realtime use this selected language ... and this whithout clicking a button. My thought was to add an action to the ComboBox, on changing the language $LAGUAGE$ get's updated whith the selection and after that i do "GoTo Label: Language" to display the dialog in the "new" language. Clicking next will go to the next step in the setup using the selected language ...

Yeah, you wouldn't be able to apply the language until the next dialog...