I used the code below to create a graphic using dot (graphviz).
digraph { node [color=Blue,shape=box] 1.1 [label=\"Frequency of t exceeds upper threshold\"]
graphviz doesn't support automatic line breaks. You have to put the \n in manually.
you can set a width and a height to a node and define it as fixedsized - this will limit the size of the node and draw only as much text as fits into the node