The “Frozen Line” is a horizontal line segment which moves up/down when the mouse moves on one part of the screen, and which freezes when the mouse moves on the other part of your screen.
In the “Frozen Line” mode, Line Or Cross splits your screen, and shows a horizontal line segment that moves up and down with the mouse to underline text in the first document, on the left, and that freezes when you move the mouse to work in the second document, on the right. In this way, the text in the left document remains underlined, while you work in the right document, without having to point to the screen with your finger.
This feature is particularly useful for occasional translators and proofreaders allowing them to switch attention effortlessly between two documents, and for anyone involved with occasional document comparison or combined lookup and writing work (e.g. students, writers, editors).