This is the Lettertypen-menu. It contains standard commands for working with the text area in the main editor window. Of note are:
This displays the standard fonts panel, where you can choose the font and size for the text.
Shows the Styles sheet, allowing creating favorite text styles that you can quickly use via the ruler.
Displays the standard color panel, allowing a dash of color to brighten your text.
If you aren't familiar with the other commands in this menu, try them out; they are very useful.
