'Declaration Public Property DropDownResizeMode As Nullable(Of PopupResizeMode)
public Nullable<PopupResizeMode> DropDownResizeMode {get; set;}
This editor has the functionality to let the user resize the drop-down list while it's dropped down. By default value of this property is Both which will let the user resize in both directions, horizontally as well as vertically. You can set this property to None to disable resizing.
A resize element is displayed at the bottom or bottom-right corner of the drop-down depending on whether this property is set to Vertical or Both, respectively.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2