Updates a bar control.
The Invalidate method recalculates all the graphical information of the bar control and then redraws it. This method is automatically called when some changes are applied to the bar control (for example, when the appearance settings are modified, etc). This method can also be called manually when the bar control needs to be updated. This can be done when you need the control to be updated in response to custom actions that don’t lead to automatic updating.