onItemCheck

called when the checkbox inside the tree item was checked

void onItemCheck(id id,boolean state,Event e);

id	id	the id of the related item
state	boolean	the checked/unchecked state of a checkbox
e	Event	a native event object (absent when the threeState property is enabled)

tree.attachEvent("onItemCheck". function(id, state, e){
    webix.message("Item " + id + " was " + (state? "checked" : "unchecked"));
});

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