Autoupdate in filter dialogs not always working

[Cyrille Berger]

> The auto-update function in filter dialogs is not always working. In some
> dialogs (eg Brightness/Contrast) making changes in the left part will
> immediately make the preview update, in other dalogs (eg Bumpmap) pressing
> the Refresh button is required to see something change.
this a problem, I will fix it (I have allready fix one or two)

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--- Cyrille Berger ---