Map Features
The 'Map Features' tab-page controls the map center-position, and Gray Line plotting. It is split into two panels:
1/ 'Lock Map Center-Position' - You can choose to lock the Map Center-Position to the current position of the Sun, or you can lock the Map Center-Position to a specified Longitude-Value. The current position of the Sun will depend on current value of the program's master clock, as set in the 'Set Date and Time for the Program Operation' panel of the 'Date Time' tab-page. If the map center-position is locked to the sun position, the sun and the analemma will always stay in the center of the map, and the map will move behind it every minute. If the map center-position is locked to a specified Longitude-Value, the map will not move at all, but the sun and the analemma will.
2/ 'Gray Line Plotting' - This plots the regions of the earth that are in darkness, and those that are in daylight. The line between the two, known as the 'Gray Line Terminator' has a shape that varies over the seasons. It is of a special interest to Amateur Radio Operators, as they can take advantage of the special propagation effects that can occur when both stations are located on the Terminator Line, enabling low-power communications over many thousands of kilometers. The Gray Line overlay can be either a view of the Earth at night, or a solid color of your choosing. To change the solid color, click the colored box next to the words 'Solid Color'. To set the transparency of the Terminator, and the width of its leading edge, use the controls provided. When the 'Gray Line' checkbox is selected, the GrayLine overlay on the World Map will automatically refresh and update every minute. The Gray Line is the first item to be added to the selected Base Map before other processing, and, as it is not classed as a 'Map Layer', its stack-position can not be altered like other map-layers.
Useful Tip
If you want to see the Gray Line but do not want it dominating other features on the map, then the solid color with low transparency is the best option to choose. Try 'Solid Color' with the transparency set to '25'.