Set the undo levels of the Image Editor. Display or Hide a layer from viewing will also be counted as an action. Please note that setting higher levels of undo will use up a lot of computer memory and slow down the program.
When adding text to an image using the Add Text Dialog in the Image Editor, the drop down menu will show the font names in their font if this option is selected. When this option is applied, the program will scan for currently installed fonts and cache the information to speed up displaying the font names in the Add Text Dialog. Each time the Add Text Dialog is opened, the program will check whether there are new fonts added and cache that information too.