When use toolbarbutton with nolabel. The blur box is wider than expected. Because it contains a " ". The code is "toolbarbutton.js":

domContent_: function()

{ var label = zUtl.encodeXML(this.getLabel()), img = this.getImage(); if (!img) return label; img = '<img src="' + img + '" align="absmiddle" />'; var space = "vertical" == this.getOrient() ? '<br/>' : ' '; return this.getDir() == 'reverse' ? label + space + img : img + space + label; }

,

Please ignore the space when label is empty.