title: UML - Showing dependency in concurrent state diagrams
body: <p>I'm modeling a user interface in which there is a 3 by 3 grid. Each square in the grid is a state [<strong>edit:</strong>] except for the (left, top) and (middle, top) squares, which together are a single state [<strong>/edit</strong>], and the initial state is the center (where the mouse cursor "starts"). When the mouse cursor passes over a boundary into a new state, that state's events are triggered.</p>
  
  <p>I'm considering modeling the axes individually, so there will be an X state and a Y state; however, how can I map an X state and a Y state back into one of the 9 square states of the grid (in the state diagram, that is)? In other words, how can I show that the actual, final state depends on (is a composition of) both the X state and the Y state? Is there a better way for me to do this?</p>
  
  <p>Please advise.</p>
  
  <pre><code>___________________
  |           |     |
  |     1     |  2  |
  |___________|_____|
  |     |     |     |
  |  3  |  4  |  5  |
  |_____|_____|_____|
  |     |     |     |
  |  6  |  7  |  8  |
  |_____|_____|_____|
  </code></pre>