The graphical maps of heavily annotated sequences can get busy in a hurry. You may end up with so many features overlapping a specific location on a sequence that the graphical images for those features “pile up” on top of one another at the top or bottom of the display. While this can happen with heavily annotated sequences, it is most often encountered with Reads in an Align To Reference window, something like this;
The reason this occurs is because MacVector tries to ensure that the Map graphics are drawn in a reasonable amount of time and also wants to ensure that the maps do not have an inordinate amount of white space. Accordingly, it limits the number of “layers” of graphics to be displayed. If a graphical item will not fit in the available space without overlapping another item, it is placed on the uppermost (or lowermost) line, where you will often see features “piling up” on top of each other. To fix this, you can adjust the number of layers using the MacVector | Preferences | Map View panel and changing the Maximum Levels setting;
Changing this to 30 cleans up this particular display;
This is an article in a long running series of tips to help you get the most out of MacVector. If you want to get notified every time a new tip gets published, follow us @MacVector on twitter (or check the feed for the hashtag #101MacVectorTips) or like us on Facebook.