Shows or hides the grid header rows. The header rows are visible by default.
var value = obj.getHeaderVisible();
obj.setHeaderVisible(value);
obj.onHeaderVisibleChanging = function(value){...};
obj.onHeaderVisibleChanged = function(value){...};
obj.onHeaderVisibleError = function(value){...};
obj.setHeaderVisible(true);
Grid templates: headers
Header model: count, indices, visible, height
Visible properties: selector, header, footer