Using easeljs? To prevent element selection on clicks to canvas...

gistfile1.js

// prevent default selection when canvas is clicked!
// does not interfere with catching events in easeljs apis

<canvas id="appCanvas"></canvas>

document.getElementById("appCanvas").addEventListener( "mousedown" , function(e){ e.preventDefault(); } , false );
document.getElementById("appCanvas").addEventListener( "mouseup" , function(e){ e.preventDefault(); } , false );