Steps to Reproduce

    <spreadsheet id="ss" height="100%" width="100%"  maxVisibleRows="150" maxVisibleColumns="40" showContextMenu="true"/>

Current Result

zss.wpd:13539 Uncaught TypeError: Cannot read property 'element' of undefined
at init.afterSize (zss.wpd:13539)
at _invoke (zk.wpd:16329)
at init.fire (zk.wpd:16312)
at _fire (zk.wpd:16455)
at Object.fireDown (zk.wpd:16672)
at Object.fireDown (zk.wpd:18432)
at Object.fireSized (zk.wpd:19242)
at init.replaceHTML (zk.wpd:21978)
at mtBL0 (zk.wpd:26017)
at mtBL (zk.wpd:25988)

Expected Result

no error

Debug Information

zcss.setRule(this.getSelectorPrefix() + " .dropdown-menu.colorpicker-element", "max-height", this.$n().offsetHeight - this._toolbar.element.offsetHeight + "px", true, this.getSheetCSSId());

this._toolbar is null.
It's better to provide a method like this._toolbar.getHeight() return 0 when the toolbar is hidden.