The display of the horizon can be toggled on and off with the pull down menu. To change the display attributes of the horizon the user needs to go to the layer manager.

Upon double clicking the horizon icon the following panel will appear.

If the No Fill button is selected then the horizon will just be a line around the edge of the map.
If Line Fill is set then the entire horizon will be filled with a line of the style choosen, at the angle and color of the middle section.
The Solid Fill selection will fill the entire horizon in with whatever fill color is currently shown in the color well.

The current color is shown in the color well. Clicking in the well will bring up the color selection patch.

To change the color of the horizon lines just choose the desired color in the patch and drag it into the well. Please note that no color patch will follow the cursor, only when you release the mouse in the well will the color appear.

As an alternative to removing the horizon is to select the hide radio button. If a layer is hidden it will remain in the layer manager but will not be plotted.