I am working with a shapefile of streams in my state. Is there a way to cause okmap to discard information that is outside of the current visible screen area when importing the file? The shapefile is large and causes okmap to become very slow when zooming or scrolling.
One way is to draw a rectangle with Shift+mouse over the area of interest. Then invert the selection with the Invert Selection context menu. Then delete the selected elements with the Selected Objects - Delete Selected - Vector Data context menu. Any lines or polygons outside the selected area will be retained because they are the continuation of the elements within the area.