How to hide the focus rectangle which gets displayed on the selected tab?

The focus rectangle can be hidden by setting the FocusOnTabClick property to false. This can be done programmatically using the code snippet given below.

this.tabControlAdv1.FocusOnTabClick = false;
Me.tabControlAdv1.FocusOnTabClick = False

NOTE

The TabControlAdv.GetTabRect method is used to get the Rectangle region of a Tab in client co-ordinates, given it’s TabIndex.