How do I set custom indicators to denote white spaces in EditControl ?

You could set custom indicators for white spaces by using the EditControl's LineFeedString, TabString and SpaceChar properties as shown in code below.

C#

this.editControl1.LineFeedString = "LF";

this.editControl1.TabString = "TAB";

this.editControl1.SpaceChar = 's';

VB

Me.editControl1.LineFeedString = "LF"

Me.editControl1.TabString = "TAB"

Me.editControl1.SpaceChar = 's'

Note that the EditControl's ShowWhiteSpaces property has to be set to true for this purpose.