I've been meaning to blog about this forever, and now I finally will. In FSX we implemented the ability to customize the information shown at the top of the screen when you press "shift+z."
In the [CONTROLS] section of fsx.cfg there are headings of [TextInfo.1] [TextInfo.2] [TextInfo.3] and [SlewTextInfo.1] [SlewTextInfo.2] [SlewTextInfo.3]. These sections define what will be seen each time you press shift+z when in normal or slew modes. You can create as many of these as you can stand to cycle through.
Under each of the sub-sections described above are variable names followed by =X,X where the X's are numbers. These numbers define the line and placement on the line. So -
means that on the first press of shift+z the latitude will be displayed on line one in the first spot on the line and Longitude will be displayed on the same line just to the right of latitude.
In the example below, on the third press of shift+z, there are six different values on the first line and four values on the second line.
You can have as many lines of information as you want on any given press of shift+z, but you do need to be aware of how much horizontal space a given line will take up across the screen.
Below is the list of variables you can display using shift+z. Using the format described above, you can put them in any order you want. I personally am using "HeadingTrue" on my slew info because occasionally we want to aim with the aircraft to help define an appropriate heading for something in a mission and all the mission objects are based on true heading instead of magnetic heading (the variable of just "Heading" is actually magnetic heading and is displayed as MAG on-screen). I also find TrueAirspeed and AltitudeAGL helpful on occasion as well.