Perl in a Nutshell, 2nd Edition

Marks

A mark is a particular position between characters in a Text widget. Once you create a mark, you can use it as an index. The gravity of the mark affects to which side the text is inserted. Right gravity is the default, in which case the text is inserted to the right of the mark.

The two marks that are automatically set are insert and current. The insert mark refers to the position of the insert cursor. The current mark is the position closest to the mouse cursor.

The following methods are defined for marking:

markGravity

Sets the gravity of a mark. For example:

$text->markGravity('insert', 'left');

markNames

Returns a list of all marks defined for the Text widget.

markSet

Creates a mark at a specified index:

$text->markSet('saved', 'insert');

markUnset

Deletes mark(s) from the Text widget:

$text->markUnset('saved');

Note that you cannot delete the insert or current marks.