To write reusable routines that work with multiple types of controls, test the control type using the TypeName function in place of the TypeOf…Is statement. For example, take a look at this routine-you can reuse it in another project only if you also add the RichTextBox control to the Components list:

 ' save the selected text to an open file' works with TextBox and RichTextBox controlsSub SaveSelectedText(ctrl As Control, filenum As Integer)	If TypeOf ctrl Is TextBox Then		Print #filenum, ctrl.SelText	ElseIf TypeOf ctrl Is RichTextBox Then		Print #filenum, RichTextBox1.SelRTF	End IfEnd Sub

To avoid this problem and gain additional benefits such as the ability to use a Select Case block, use the TypeName function instead:

 Sub SaveSelectedText(ctrl As Control, filenum As Integer)	Select Case TypeName(ctrl)		Case "TextBox"			Print #filenum, ctrl.SelText		Case "RichTextBox"			Print #filenum, RichTextBox1.SelRTF	End SelectEnd Sub