ref: df31bc7a515a56b2322a097bda8f1aa510a7b9da
dir: /html/tracks.html/
Tracks <p> Complete the track from A to B so that the rows and columns contain the same number of track segments as are indicated in the clues to the top and right of the grid. There are only straight and 90-degree curved rail sections, and the track may not cross itself. <p> Left-click on an edge between two squares to add a track segment between the two squares. Right-click on an edge to add a cross on the edge, indicating no track is possible there. <p> Left-click in a square to add a colour indicator showing that you know the square must contain a track, even if you don't know which edges it crosses yet. Right-click in a square to add a cross indicating it contains no track segment. <p> Left- or right-drag between squares to lay a straight line of is-track or is-not-track indicators, useful for filling in rows or columns to match the clue.