DOH! 
Just found it.
It appears that the LCD panel I am talking to sends a CR out every second. Why I don't know. Nothing in the documentation about it.
So there is always Serial data available. 
It also sends a CR after each command, Which is what I was listening for to know that all the data was in. Then I would do something with the data. so I will need to figure out how to tell the difference so ready is not true each time a CR comes in.
But thanks anyways, it was inspiring 
flush is for the output buffer only.
Aha. OK. But that raises the question if it waits until all data is sent, again, whats it for? Once all data is sent, is it not clear?