The PubChem sketcher main window, with loaded compound. The sketcher contains three visible sub-window sections: a drawing area (right), a mode control pad (left), and a status line (top).
Mouse events are not the only events associated with drawing area coordinates. Some keyboard shortcuts also use coordinates, such as ctrl-v for pasting a structure encoding from the clipboard onto the drawing area. Other keyboard shortcuts simply change the sketcher mode. A description of all keyboard shortcuts is available in the PubChem Sketcher help page http://pubchem.ncbi.nlm.nih.gov/sketch/sketchhelp.html