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RichTextBox.ShowSelectionMargin Property

Gets or sets a value indicating whether a selection margin is displayed in the RichTextBox.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public bool ShowSelectionMargin { get; set; }

Property Value

Type: System.Boolean
true if a selection margin is enabled in the control; otherwise, false. The default is false.

You can use this property to enable the user to easily select lines of text in the RichTextBox. The selection margin is added to the left side of the RichTextBox. This margin makes it easier for the user to select text starting on the left side of the control. The user can click in the selection margin to select a single line of text or double-click to select the entire paragraph that the line double-clicked is contained within.


If the ShowSelectionMargin property is set to true, setting the ScrollBars property to RichTextBoxScrollBars.Horizontal, RichTextBoxScrollBars.Vertical, or RichTextBoxScrollBars.Both will not cause scroll bars to be displayed. In order to display scroll bars while the ShowSelectionMargin property is set to true, set the ScrollBars property to RichTextBoxScrollBars.ForcedHorizontal, RichTextBoxScrollBars.ForcedVertical, or RichTextBoxScrollBars.ForcedBoth.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.