I added a new SplitHandleWidth property to GridView.cs.
The following sample demonstrates the SplitHandleWidth property and is a slightly modified version of
https://examples1.ext.net/#/GridPanel/ArrayGrid/Simple/
Example
<ext:GridPanel
ID="GridPanel1"
runat="server"
StoreID="Store1"
StripeRows="true"
Title="Array Grid"
TrackMouseOver="true"
Width="600"
Height="350"
AutoExpandColumn="Company">
<ColumnModel runat="server">
<Columns>
<ext:Column ColumnID="Company" Header="Company" Sortable="true" DataIndex="company" />
<ext:Column Header="Price" Sortable="true" DataIndex="price">
<Renderer Format="UsMoney" />
</ext:Column>
<ext:Column Header="Change" Sortable="true" DataIndex="change">
<Renderer Fn="change" />
</ext:Column>
<ext:Column Header="Change" Sortable="true" DataIndex="pctChange">
<Renderer Fn="pctChange" />
</ext:Column>
<ext:Column Header="Last Updated" Sortable="true" DataIndex="lastChange">
<Renderer Fn="Ext.util.Format.dateRenderer('m/d/Y')" />
</ext:Column>
</Columns>
</ColumnModel>
<View>
<ext:GridView runat="server" SplitHandleWidth="10" />
</View>
<SelectionModel>
<ext:RowSelectionModel runat="server" SingleSelect="true" />
</SelectionModel>
</ext:GridPanel>
The new property has been committed to svn and will be publicly available with the next release (0.8.2?)
Hope this helps.