Append: when setting the width of both sides, it is best to set them to 7 ×, 3 ×, so that you can drag back and forth.
<Usercontrol X: class = "G. module. intermediary. navigation "xmlns =" http://schemas.microsoft.com/winfx/2006/xaml/presentation "xmlns: x =" http://schemas.microsoft.com/winfx/2006/xaml "xmlns: D =" http://schemas.microsoft.com/expression/blend/2008 "xmlns: MC =" http://schemas.openxmlformats.org/markup-compatibility/2006 "MC: ignorable =" D "xmlns: tr = "http://schemas.telerik.com/2008/xaml/presentation" xmlns: SDK = "htT P: // schemas.microsoft.com/winfx/2006/xaml/presentation/sdk "> <grid X: Name =" layoutroot "background =" white "> <grid. resources> <resourcedictionary source = "/glodon. module. theme; component/appresource. XAML "> </resourcedictionary> </grid. resources> <grid. rowdefinitions> <rowdefinition Height = "0"> </rowdefinition> <rowdefinition Height = "*"> </rowdefinition> <rowdefinition Height = "0"> </rowdefinition> </Grid. rowdefinitions> <grid. columndefinitions> <columndefinition width = "0"> </columndefinition> <columndefinition width = "200"> </columndefinition> <columndefinition width = "10"> </columndefinition> <Partition width = "*"> </columndefinition> <columndefinition width = "0"> </columndefinition> </grid. columndefinitions> <TR: radtreeview X: Name = "radpanelbar" grid. row = "1" selectionchanged = "radpanelbar_se Lectionchanged "grid. column = "1" verticalalignment = "stretch" borderbrush = "# ffcbd8e8" borderthickness = "2"> <TR: radtreeviewitem header = "qualification" fontweight = "bold" isexpanded = "true" X: Name = "radpanelzizhi"> </TR: radtreeviewitem> <TR: radtreeviewitem header = "rating level" fontweight = "bold" isexpanded = "true" X: Name = "radpanelgrade"> <TR: radtreeviewitem header = "90 + points" X: name = "gradetop"/> <TR: radtreeviewitem header = "80 Minutes ~ 90 points "X: Name =" grademinddle "/> <TR: radtreeviewitem header =" 80 points or less "X: Name =" gradeunder "/> </TR: radtreeviewitem> <TR: radtreeviewitem header = "region" isexpanded = "true" fontweight = "bold" X: Name = "radpaneldiqu"> </TR: radtreeviewitem> </TR: radtreeview> <SDK: gridsplitter grid. row = "1" grid. rowspan = "3" grid. column = "2" grid. columnspan = "1" background = "# dcecfe" horizontalalignment = "stretch" verticalcontentalignment = "stretch"> </SDK: gridsplitter> <scrollviewer verticalscrollbarvisibility = "Auto" name = "list" grid. row = "1" grid. rowspan = "1" grid. column = "3" grid. columnspan = "1"> </scrollviewer> </GRID>