Defines whether items in a WPFItemsControl, like WPFComboBox or WPFListBox, are pre-filled during recording and playback. WPF itself lazily loads items for certain controls, so these items are not available for Silk4J if they are not scrolled into view. Turn pre-filling on, which is the default setting, to additionally access items that are not accessible without scrolling them into view. However, some applications have problems when the items are pre-filled by Silk4J in the background, and these applications can therefore crash. In this case turn pre-filling off.