When Paused=false, the control will redraw anyway and so calling Invalidate has no effect. However, when Paused=true, the control will not normally redraw itself. Calling Invalidate() will cause the control to schedule a Draw without an Update.

This method can be called from any thread.

Multiple calls to Invalidate() between Draw events are coalesced.

The policy around completed CreateResources remains unchanged; after a call to Invalidate() the Draw event will not be raised until CreateResources has completed.

Be aware, though, that the Update event will not be raised. This opens up the possibility of a Draw occurring before the first Update if the control is created with Paused=true.

Reference