Use default height (indicated by -1) instead of 30 when creating wx ComboBox, otherwise wx warns that modern versions of OSX (10.5+) don't support vertically resizeable combo boxes
Calling SetFocusFromKbd() on Mac in wx 2.7 causes text fields to lose focus whenever the mouse moves. These calls are no longer necessary to ensure canvas draws properly, removing.
Ensure empty char buffers are initially null-terminated to prevent odd, potentially crash-inducing sprintf output
Version to 1.7; ensure valid polyline in OnAddFirstGraph()