hflex does not take scrollbars into account

<?init class="org.zkoss.zkplus.databind.AnnotateDataBinderInit" arg0="./win"?>
<?page title="Scrollable Div with a listbox" contentType="text/html;charset=UTF-8"?>
<window id="win" border="none" height="100%" width="100%">
	<div style="overflow:auto" height="100%" width="100%" vflex="1">
		<listbox id="qssList" rows="10" hflex="1">
			<listhead>
				<listheader label="Col1" />
				<listheader label="Col2" width="70px" />
				<listheader label="Col3" width="70px" />
				<listheader label="Col4" width="70px" />
				<listheader label="Col5" width="200px" />
			</listhead>
		</listbox>
	</div>
</window>

<?init class="org.zkoss.zkplus.databind.AnnotateDataBinderInit" arg0="./win"?>
<?page title="Scollable div with a grid" contentType="text/html;charset=UTF-8"?>
<window id="win" border="none" height="100%" width="100%">
	<div style="overflow:auto" height="100%" width="100%" vflex="1">
		<grid zclass="none" hflex="1">
			<columns>
				<column width="120px" />
				<column />
				<column width="120px" />
				<column />
			</columns>
			<rows>
				<row>
					<label value="Label1:" />
					<textbox maxlength="6" width="100px" />
					<label value="Label2:" />
					<datebox width="100px" format="dd.MM.yyyy" />
				</row>
				<row spans="1,3">
					<label value="Label5:" />
					<div id="div5" />
				</row>
				<row>
					<label value="Label6:" />
					<datebox width="100px" format="dd.MM.yyyy" />
					<label value="Label7:" />
					<checkbox />
				</row>
				<row spans="1,3">
					<label value="Label7:" />
					<hbox align="center" pack="stretch">
						<intbox cols="3" width="30px" />
						<label value="label8" />
					</hbox>
				</row>
			</rows>
		</grid>
	</div>
</window>