I modified Daniil's sample. You can use it to start:
<%@ Page Language="C#" %>
<%@ Register Assembly="Ext.Net" Namespace="Ext.Net" TagPrefix="ext" %>
<!DOCTYPE html>
<html>
<head runat="server">
<title>Ext.NET v2 Example</title>
<script type="text/javascript">
var onRender = function (panel) {
var leftDockedItems = panel.getDockedItems("header[dock='left']"),
leftDockedItem;
if (leftDockedItems.length > 0) {
leftDockedItem = leftDockedItems[0];
leftDockedItem.on("click", onLeftDockedItemClick, panel);
var task = new Ext.util.DelayedTask(function () {
leftDockedItem.addTool({
"type": "left",
listeners: {
click: {
fn: onLeftDockedItemClick,
scope: panel
}
}
});
});
task.delay(10);
} else {
panel.on("collapse", onRender, panel, { single: true });
}
};
var onLeftDockedItemClick = function () {
var me = this;
me.ownerCt.items.each(function (item) {
if (me !== item && item.collapse && !item.collapsed) {
item.collapse();
}
});
me.expand();
};
</script>
</head>
<body>
<ext:ResourceManager runat="server" SourceFormatting="True" />
<ext:Window runat="server" Width="600" Height="150">
<LayoutConfig>
<ext:HBoxLayoutConfig Align="Stretch" DefaultMargins="2 0" />
</LayoutConfig>
<Items>
<ext:Panel
runat="server"
ID="Panel1"
Flex="1"
Title="Panel 1"
CollapseDirection="Left"
HideCollapseTool="true"
AnimCollapse="false">
<Listeners>
<Render Fn="onRender" />
</Listeners>
<HeaderConfig TitlePosition="0">
<Items>
<ext:Tool runat="server" Type="Left"></ext:Tool>
</Items>
</HeaderConfig>
</ext:Panel>
<ext:Panel
runat="server"
ID="Panel2"
Flex="1"
Title="Panel 2"
CollapseDirection="Left"
HideCollapseTool="true"
Collapsed="true"
AnimCollapse="false">
<Listeners>
<Render Fn="onRender" />
</Listeners>
<HeaderConfig TitlePosition="0">
<Items>
<ext:Tool runat="server" Type="Left"></ext:Tool>
</Items>
</HeaderConfig>
</ext:Panel>
<ext:Panel
runat="server"
ID="Panel3"
Flex="1"
Title="Panel 3"
CollapseDirection="Left"
HideCollapseTool="true"
Collapsed="true"
AnimCollapse="false">
<Listeners>
<Render Fn="onRender" />
</Listeners>
<HeaderConfig TitlePosition="0">
<Items>
<ext:Tool runat="server" Type="Left"></ext:Tool>
</Items>
</HeaderConfig>
</ext:Panel>
</Items>
</ext:Window>
</body>
</html>