touchgfx::ScrollableContainer::childGeometryChanged() method

@fn virtual void ScrollableContainer::childGeometryChanged(); Used to signal that the size of one or more children have changed. This function can be called on parent nodes to signal that the size of one or more of its children have changed. Currently only used in ScrollableContainer to redraw scrollbars when the size of the scrolling contents changes. @see Drawable::childGeometryChanged