Tree lines, as the name suggests, are the lines connecting the nodes of a treeview displaying the relationship between parent and child nodes clearly.

TreeView allows you to display or hide the tree lines by setting the ShowLines property provided by the TreeViewStyles class to true or false. In addition, the control enables you to perform customizations, as follows:

• Color: Change the color of the connected lines between the nodes by setting the LinesColor property of the TreeViewStyles class.
• Width: Set the width of the tree lines by setting the LinesWidth property of TreeViewStyles to integer values.
• Style: Specify the style of the tree lines by setting the LinesStyle property of TreeViewStyles from the DashStyle enumeration.

The following image shows TreeView with the tree lines customized with respect to their color, width, and style.

The following code snippet enables the visibility of the tree lines and customizes them in terms of their width, color, and style.

'set the ShowLines property
C1TreeView1.Styles.ShowLines = True

'set the LinesWidth property
C1TreeView1.Styles.LinesWidth = 2

'set the LinesColor proprerty
C1TreeView1.Styles.LinesColor = System.Drawing.Color.Orange

' set the LinesStyle property
C1TreeView1.Styles.LinesStyle = Drawing2D.DashStyle.Solid

// set the ShowLines property
c1TreeView1.Styles.ShowLines = true;

// set the LinesWidth property
c1TreeView1.Styles.LinesWidth = 2;

// set the LinesColor proprerty
c1TreeView1.Styles.LinesColor = System.Drawing.Color.Orange;

// set the LinesStyle property
c1TreeView1.Styles.LinesStyle = System.Drawing.Drawing2D.DashStyle.Solid;